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Response Surface Methodology-Optimized FL0.1@ZIF-8 Fluorescent Probe for High-Throughput Capsaicin Analysis in Chili Products
Capsaicinoids are a group of naturally occurring organic compounds responsible for the pungency of chili. This study aimed at exploring a novel approach with multivariate-assisted Response Surface MethodologyBox Behnken Design (RSM-BBD) optimized fluorescent probe (FL0.1@ZIF-8) for the detection of capsaicin. The probe was solvothermally synthesized and characterized using XRD, FTIR, and SEM to confirm the successful incorporation of fluorescein (FL) into ZIF-8. The experimental parameters, including pH, concentration of the probe, and reaction time, were systematically optimized via RSM-BBD to enhance the sensitivity of FL0.1@ZIF-8. The results demonstrated a quenching response of FL0.1@ZIF-8 emission with capsaicin. The limit of detection (LOD) and limit of quantification (LOQ) were calculated and found to be 1.5 ?M and 4.9 ?M, respectively. The outcome of the study identifies efficient electronic factors as major contributors to the development of FL0.1@ZIF-8 with promising possibilities for the detection of chili hotness for food pungency evaluation, quality control, and assurance in the food industry. 2026 American Chemical Society -
Integrated 3D-Printed Detector for Rapid Near-IR Turn-On Colorimetric and Fluorescent Detection of Phosgene
Phosgene is a widely used yet highly hazardous compound that poses serious risks to human health and public safety due to its potential for misuse and accidental release. Therefore, developing an accurate and highly sensitive detection method is of critical importance. In this work, we have synthesized a sulfo-cyanine-based dye (CyNH) for the selective rapid detection (<1 min) of phosgene by Near-IR turn-on colorimetric and fluorescence responses. Notably, CyNH exhibited a 3-fold fluorescence enhancement at 756 nm accompanied by a distinct color change from light blue to dark blue by the appearance of strong absorption signal at 600 nm, with a detection limit of 1.17 ?M. To enable on-site detection, a 3D-printed sensor of the CyNH-coated 3D-printed substrate was developed, which shows visible color changes upon exposure to phosgene. Furthermore, integration of this sensor with a smartphone camera and its processing capabilities allows for real-time quantification of phosgene concentrations by eliminating the need for costly analytical instruments. To the best of our knowledge, the development of an NIR probe enabling dual colorimetric and fluorescent NIR detection of phosgene using a 3D-printed sensor is scarcely reported. This innovative 3D-printed, smartphone-assisted sensing platform offers a practical and sustainable approach for future phosgene detection applications in various fields. 2026 American Chemical Society -
Mechanoluminescence of PolymerOrganic Composites under Strain and Hydrostatic Pressure
The development of underwater-based Internet of Things has drawn much attention to fluorescence sensors for crucial technological advancement. Therefore, the technologies for underwater mechanoluminescence (ML) sensing have created various applications for sensors and self-powered waterproof displays. However, developing single-molecule-based intrinsically adaptive materials capable of responding to multiple stimuli with high sensitivity remains a challenge. Herein, a flexible sensor based on the fluorescent ligand DHN was fabricated using a PVDF polymer matrix to form PVDH, enabling the exploration of external-stimuli-responsive fluorescence enhancement under mechanical strain and underwater pressure. For PVDH, the transition from crystalline to amorphous state by mechanical stimuli boosted its photoluminescence by ?75%, and stretching (strain ?16%) the sensor boosted its photoluminescence by ?145%, which is due to the formation of molecular aggregates in the amorphous state. Additionally, the increase in ML correlated with an output voltage of ?4 V of the fabricated device under mechanical stress. The in-depth density functional theory (DFT) calculations further support the experimental observation by studying the charge distribution and orbital overlapping in the DHN ligand. Furthermore, the film shows clear visualization when subject to underwater pressure and stable fluorescence upon exposure to different impurities. Therefore, this study reveals the use of fluorescence and mechanochromic properties of the ligand for designing advanced underwater sensors for visualization and communication. 2025 American Chemical Society -
Negative-Valent Palladium-Stabilized CoPdN Thin Films as a Catalyst for the Oxygen Evolution Reaction
The urgent global demand for sustainable energy drives the search for durable and efficient electrocatalysts for water splitting. Cobalt mononitride (CoN) stands out due to its earth abundance, high conductivity, and corrosion resistance, but its thermodynamic instability often results in cobalt-rich secondary phases. Here, we report a scalable reactive cosputtering approach for the controlled synthesis of CoN thin films, along with palladium (Pd) incorporation to enhance activity and stability. Pd doping induces a negative valence state and promotes electron transfer from nitrogen to Pd sites, thereby refining the microstructure, redistributing charge, and shifting the d-band center away from the Fermi level. These synergistic effects reduce the overpotential from 470 to 360 mV at 10 mAcm2 in a sample coated on the ITO substrate and deliver markedly improved long-term OER stability with increased catalytically active sites. The turnover frequency showed nearly twice the intrinsic activity with Pd doping. This work establishes Pd-doped CoN as a high-performance, durable electrocatalyst, offering a scalable pathway toward efficient water splitting technologies. 2025 American Chemical Society -
Copper-Embedded Aminothiazole-Engineered Nanocatalyst for Electrochemical Reduction of CO2to Alcohols
The electrochemical reduction of CO2(CO2ER) to value-added products such as methanol and ethanol is gaining significant attention as a sustainable solution to excess carbon footprints and increased energy demand. To this end, we present the electrochemical preparation of a copper-coordinated aminothiazole metallopolymer (CAM), which fosters efficient charge transfer through multiple redox couples. The prepared CAM electrode displayed excellent efficiency toward the selective production of methanol and ethanol at a low potential of ?0.73 V vs RHE, marking a significant achievement. Notably, the incorporation of Cu species along with the nitrogen- and sulfur-containing heterocyclic group of polyaminothiazole (AMp) allowed easy stabilization of the intermediates over the electrode surface, with a marked shift from C1to C2product formation. The study explores the dynamic aspects of the electrocatalyst leading to such pronounced selectivity. These findings are pivotal in encouraging more research toward the profitable production of electrofuels, particularly for decarbonizing the transportation and industrial sectors. 2025 American Chemical Society -
Nature-Inspired Photoresponsive Bionic Robots Using the TelluriumMoS2Graphene Hybrid Structure
Motivated by biological natural living things, multifunctional soft robots have become an exciting system that can navigate by overcoming difficult situations. Photothermal self-excited actuators offer potential for self-driven soft robotics since they provide wireless power and control. However, it remains challenging to achieve photoresponsive actuation, which can serve as basic component in soft-bioelectronics. Tellurium (Te)-based nanostructures can be a promising candidate and offer greater infrared-photoresponsive properties. Therefore, in this work, we have systematically studied the effect of Te nanoparticles on the two-dimensional hybrid structure for advanced photoresponsive actuation under near-infrared (NIR) light exposure, which reaches ?85 C within ?5 s. This approach substantially improves the photothermal behavior including thermal conversion (? ? 12.7%), large bending (?5.74 cm1), and fast response (?250 ms), by increasing the internal temperature of the system. Leveraging this strategy, we have developed soft bionic Dragonfly, and it demonstrates multiple performances including controllable bending and wing movement at a maximum speed. The density functional theory (DFT) calculation and in situ Raman spectroscopy measurement reveal the photoactuation behavior of the system. This research proposes new idea of hybrid structure and exhibits substantial photothermal conversion efficiency with significant deformation for soft bionic applications. 2026 American Chemical Society -
2D MnTe/rGO Hybrid Structure for Moisture Energy Harvesting
The development and widespread use of wind, solar, geothermal, and other renewable energy sources have increased the supply of clean, green electricity while reducing environmental strain. Extracting renewable energy from continuously available humid air is a potential pathway for a sustainable future. Here, we explore the use of two-dimensional (2D) manganese telluride (MnTe) hybrid structures with reduced graphene oxide (rGO), for absorbing moisture and atmospheric humidity. The resistance of the 2D hybrid structures increases with moisture exposure and decreases upon moisture removal, suggesting their suitability for humidity-controlled power devices. The optimized thickness of the composites exhibits the highest response under moisture exposure due to the interfacial charge transfer. The MnTe/rGO hybrid structure also absorbs a low amount of moisture from ambient humid (RH ? 90%) air, resulting in electrical output up to ?125 mV within ?15 s. Furthermore, the study hints at the potential of 2D MnTe for energy harvesting from moisture and sustainable power sources. We used density functional theory (DFT) calculations to understand the systems ability to transfer charge. In situ Raman spectroscopy and imaging techniques further confirm the effect of moisture on a hybrid surface. These findings lay the foundation for developing an efficient nanogenerator that can find applications in wearable electronics and environmental monitoring systems. The study contributes to materials science and offers a pathway towards developing sustainable and efficient electronic devices and environmental monitoring systems. 2025 American Chemical Society. -
Plasmonic Ag-Integrated Mesoporous Mn2O3TiO2 Thin Films for Efficient Solar Hydrogen Production
The present work describes the synthesis of mesoporous Mn2O3TiO2 (TiMn) and Ag-integrated TiMn (TiMnAg) nanocomposites, and their superior photocatalytic activity in a thin-film form was demonstrated for solar H2 generation in direct sunlight. The integration of metallic Ag and TiMn significantly enhanced solar H2 production due to the combined effect of Schottky junction and heterojunction formation. The PIRET (plasmon-induced resonance energy transfer) effect of Ag and the consequent energy transfer to the surrounding lattice, and heterogeneous distribution of metal ions on the TiO2 surface with possible synergistic interactions among them, are additional reasons for efficient solar-to-chemical energy conversion. TiMnAg-1 (0.5 wt % Ag-loaded on TiMn) and TiMn-3 (TiO2:Mn = 1:0.03 mol ratio) showed the highest H2 production rate (9.05 mmolh1g1), which is 60 times higher than that of bare TiO2 (0.16 mmolh1g1). TiMnAg-1 fabricated in a thin-film form shows 5.2 times higher solar H2 production activity than its powder counterpart. The interconnected mesoporous network in TiMnAg-1 is an additional advantage, which enhances diffusion and mass transfer during the reaction. The plausible photocatalytic reaction mechanism of the TiMnAg nanocomposites involves direct energy and electron transfer from metallic Ag nanoparticles and Mn2O3 species, respectively, to TiO2, which is then utilized for the reduction of H+ to H2. 2026 American Chemical Society -
Lattice Distortion Suppressed in MoO3 by Incorporating Minor Impurities of rGO: Strategy for Enhanced Electrocatalytic Hydrogen Evolution
Structural stability is critical for improving the electronic properties and charge-transfer efficiency of the catalyst, directly contributing to its enhanced electrocatalytic hydrogen evolution reaction (HER) activity. In this study, orthorhombic MoO3 and rGO-MoO3 catalysts were synthesized by using a straightforward hydrothermal method, and they demonstrated excellent activity for electrochemical water splitting for hydrogen generation. In this study, conventional laboratory techniques, except for Raman spectroscopy, were unable to clearly detect or differentiate the presence and impact of a very small amount (0.5%) of rGO in MoO3. However, X-ray absorption fine structure analysis performed at the synchrotron facility provided definitive confirmation of the influence of minor rGO incorporation in this study. The analysis revealed that the incorporation of rGO suppresses lattice distortions and enhances the stability of local atomic coordination within the MoO3 framework. The Tafel slopes for MoO3 and rGO-MoO3 composite nanorods are 205 and 173 mV/dec, indicating improved reaction kinetics with rGO incorporation. The estimated specific capacitance values from the linear fit of CV at different scan rates are 2.0 mF/cm2 for MoO3 and 6.7 mF/cm2 for the rGO-MoO3 composite nanorods. Therefore, this study provides valuable insights into tuning the structural properties of materials and enhancing the HER performance through the incorporation of trace amounts of carbon-based materials, effectively suppressing lattice distortions. 2025 American Chemical Society. -
2D Materials Coated Flexible Origami for Low-Frequency Energy Harvesting
Wave energy is one of the most abundant energy sources. Triboelectric nanogenerators (TENGs) are becoming more popular for sustainable energy generation from waves. Concerning the renewable energy demands, we focus on developing cost-effective and adaptable origami-TENGs (O-TENGs) for harvesting wave energy, specifically utilizing paper-based (cellulose) materials. An origami-inspired lightweight and scalable design is proposed to create high-performance O-TENGs suitable for the complex conditions of low-frequency wave excitation. The paper-based spring-like O-TENG is coated with two-dimensional (2D) molybdenum disulfide (MoS2) nanosheets and demonstrates efficacy in harvesting mechanical energy in the ambient environment and the output performance compared with reduced graphene oxides (rGO). A detailed density functional theory (DFT) calculation was used to analyze the charge transfer mechanism in the coated origami structures. Furthermore, a barrel-shaped floating generator incorporating multiple origami TENGs is introduced to capture ocean wave energy across various frequencies, amplitudes, and directional movements. Since the coated origami structures show a good self-rebounding spring-like nature and energy harvesting properties, they are suitable for blue energy harvesting. 2025 American Chemical Society. -
PEGylated Platinum Nanoparticles: A Comprehensive Study of Their Analgesic and Anti-Inflammatory Effects
Pain and inflammation are common symptoms of a majority of the diseases. Chronic pain and inflammation, as well as related dreadful disorders, remain difficult to control due to a lack of safe and effective medications. In this work, biocompatible platinum nanoparticles with significant analgesic and anti-inflammatory action were synthesized through a wet chemical method using polyethylene glycol-400 as a capping agent and sodium borohydride as a reducing agent. The average particle size of these Pt nanospheres was determined to be 3.26 nm using TEM analysis, and X-ray diffraction confirmed their face-centered cubic crystalline structure. Fourier transform infrared and UV-visible spectroscopy confirm that Pt-NPs are coated with the PEG-400 molecule. The significantly negative zeta potential value (?26.8 mV) indicates the stability of the produced nanoparticles. In vitro cytotoxicity studies on normal cell lines show nontoxic behavior with over 96% cell viability at 100 ?g/mL of the test sample. In vitro assays of inhibition of protein denaturation and DPPH free radical scavenging elucidated the anti-inflammatory and antioxidant properties of PEGylated Pt NPs with promising EC50 values 57.99 and 9.324 ?g/mL, respectively. In vivo animal trials confirmed that PEG-capped Pt-NPs are more effective than conventional medicines. The in vivo hot plate assay for the analgesic study shows a maximum response time of 14.5 1.22 s (92.54% analgesia) at a dosage of 50 mg/kg and 13.8 0.71 s (86.05% analgesia) at a dosage of 25 mg/kg after 180 and 240 min of administration, respectively. In the rat paw edema model for anti-inflammatory activity, the PEG-capped Pt NPs exhibit significant inhibitory action, with the maximum percentage of edema inhibition at a dosage of 50 mg/kg identical to that of the aspirin-based standard medication administered at a higher dosage of 100 mg/kg, resulting in 42% inhibition, suggesting a versatile solution for inflammation and persistent pain. 2025 American Chemical Society. -
Mushroom-Derived Carbon Nanosheets for Efficient Photothermal De-Icing Applications
The green synthesis of nanomaterials has emerged as a viable alternative to traditional techniques that reduce environmental risks and the production of harmful byproducts. In this work, biomaterial derived from wild mushrooms was used to synthesize psilocybin-derived carbon nanosheets (P-CNSs). The bioactive substance psilocybin serves as a sustainable precursor that ensures an environmentally friendly synthesis procedure. Spectroscopic measurements confirm the structural and functional properties of the P-CNSs. The naturally extracted P-CNSs demonstrated substantial photothermal conversion efficiency under both visible and infrared light. Their adaptability for thermal applications was shown by their medium-specific response. Furthermore, in photothermal de-icing, P-CNSs effectively melted ice under visible light exposure, making it a crucial application. Additionally, density functional theory (DFT) and time-dependent DFT calculations were performed to optimize the structures of psilocin, baeocystin, and norbaeocystin, which show the electronic transitions responsible for the appearance of absorption and fluorescence behavior. This work draws attention to the inclusion of psilocybin in green synthesis to produce an affordable and sustainable solution for environmental issues brought to the forefront by the advantages of environmentally benign manufacture and multipurpose use, especially in thermal control and environmental remediation. 2026 American Chemical Society -
Electrochemical Transformation of Thiol-Iodine-Based Reactions toward Multiplexed Sensing Applications for Plant-Stress Hormone and Environmental Contaminant
Functionalized thiophenes are potential electroactive species that serve as efficient molecular electrochemical sensors. This work describes the fabrication of a 3-thiophene acetic acid (TAA)-modified screen-printed carbon electrode/multi-walled carbon nanotube (SPCE/MWCNT) platform via a facile electrochemical method in an aqueous medium. The effectual PT-Redox (product of TAA formed postpotentiostatic polarization) integration over SPCE/MWCNT was confirmed through various spectroscopic and electrochemical investigations. The SPCE/MWCNT showcased exceptional interaction with PT-Redox, creating a resilient platform for its precise binding, thereby enhancing the electrodeelectrolyte electroactive region, topographic roughness, electron conductivity, host response, and comprehensive electrochemical properties. The as-prepared electrode (SPCE/MWCNT@PT-Redox) was employed for the selective detection and quantification of glutathione (GT) as well as hydrazine (HyD) in an aqueous medium. The sensor showed excellent electrocatalytic oxidation responses toward these analytes, yielding a good sensitivity of 0.32 ?A mM1, a low detection limit (DL) of 0.225 ?M, a broad linear dynamic window of 0400 ?M for GT, a high sensitivity of 0.13 ?A mM1, a low DLof 0.56 ?M, and a linear window of 0350 ?M for HyD, obtained via the differential pulse voltammetry (DPV) technique. This substantiates that the modification with PT-Redox significantly boosted the electrodes interfacial activity and catalytic potential. Furthermore, the electrode exhibited robust antifouling and anti-interference traits, suggesting the composites enhanced stability and sensing capabilities for real-world applications. The captivating features, including excellent specificity, fast response dynamics, and simple sample preparation necessities of the proposed system, reveal a promising platform that accomplishes significant potential in futuristic sensing applications. 2025 American Chemical Society -
Electroreduction of CO2 to Methanol Using a Coordination-Moiety-Anchored Carbon-Based Electrode
Electrochemical reduction of carbon dioxide (CO2ER) has gained wide attention lately because of its potential to create a closed carbon loop, offering a sustainable solution toward environmental as well as energy crisis. However, the key challenge lies in the selective conversion of CO2 into electrofuels, such as methanol, which necessitates six proton-coupled electron transfers. In this work, we report the first instance of an electrochemically prepared Cu-coordinated 2,5-dimercapto-1,3,4-thiadiazole-modified carbon fiber paper electrode (CDM@CFP). The hence-engineered novel electrode was applied for the CO2ER reaction to produce methanol exclusively with an F.E. of 59.6% at a low potential of ?0.73 V versus RHE. Unlike most of the copper-based electrocatalysts, which result in multiple hydrocarbons, here, we have optimized a potential-dependent selectivity for maximum efficiency, which is a significant milestone in the field. 2025 American Chemical Society. -
Unveiling the Redox Characteristics of Rutin Trihydrate-Canvas-Based Sensor for Hydrazine Sensing in Water Samples
The inclusion of redox mediators into electrocatalytic systems facilitates rapid electron shuttling kinetics and boosts the overall catalytic performance of the electrode. This approach overcomes the sluggish reaction dynamics associated with direct electron transfer, which may be impeded by restricted analyte access to the electrodes active sites. In contrast to conventional synthetic redox mediators, naturally sourced phytomolecule rutin trihydrate (RT), extracted from apple juice, offers potential ecological advantages. This bands with green chemistry principles and sustainability in electroanalytical approaches. The current work presents an eco-friendly and direct electrochemical approach to fabricate a redox-active RT-immobilized MWCNT-infused PEDOT hybrid material-modified glassy carbon electrode (GCE/MWCNT + PEDOT@RT). The developed electrode showcased a sharp and stable redox signal at E0 = 0.63 V vs Ag/AgCl with no surface-fouling characteristics. The efficacious functionalization of RT onto MWCNT + PEDOT was corroborated by a remarkable increase in the surface characteristics, enhanced electrochemical current responses, and low charge transfer resistance. The GCE/MWCNT + PEDOT@RT exhibited highly selective and sensitive sensing responses toward the toxic and potentially carcinogenic hydrazine (HZ) via cyclic voltammetry and differential pulse voltammetry techniques, yielding a low detection limit (DL) of 1.02 ?M and a sensitivity of 0.032 ?A ?M-1 in a linear dynamic range between 0 and 1350 ?M. In addition, the method was highly efficient for HZ detection in real samples of tanker, tap, and wastewater samples, producing a good recovery of ?98%. 2025 American Chemical Society. -
Boosting Surface Coverage of CO Intermediates through Multimetallic Interface Interactions for Efficient CO2 Electrochemical Reduction
Given the inherent challenges of the CO2 electroreduction (CO2ER) reaction, solely from CO2 and H2O, it is desirable to develop selective product formation pathways. This can be achieved by designing multimetallic nanocomposites that provide optimal CO coverage, allowing for tunability in the product formation. In this work, Ag and Zn codoped-SrTiO3 (ZAST) composite immobilized carbon black (CB)-modified GCE working electrode (ZAST@CB/GCE) was developed for the electrochemical conversion of CO2 to multicarbon products. The complete reaction was carried out in a CO2-saturated aqueous system of 0.5 M KHCO3 electrolyte. A potential-dependent product selectivity was suggested based on the NMR results, wherein raising the potential value enhanced the formation of liquid products such as acetone and alcohols while suppressing competitive HER. The total Faradaic efficiency for liquid products reached an impressive 97% at a potential of ?0.6 V vs. RHE. This represents a significant advancement in acetone production pathways and valorization of CO2ER technology. 2025 American Chemical Society. -
Investigating the Electrochemical Behavior of Flowerlike-Co-Pi-Decorated Ti3C2TxMXene for Cathodic CO2Utilization: A Sustainable Approach
The rising CO2 concentration in the atmosphere has sparked the need for research communities and industries to shift toward embracing technologies prioritizing CO2 conversion and utilization. This research presents the fabrication of flowerlike cobalt-inorganic phosphate-decorated Ti3C2Tx MXene-modified carbon fiber paper (Co-Pi/Ti3C2Tx/CFP) electrode for electrochemical CO2 fixation via benzyl chloride transformation to produce industrially and pharmaceutically important phenylacetic acid (PAA). The multilayered Ti3C2Tx, having a large specific surface area, functions as the nucleation centers for the deposition of Co-Pi and enhances its physical, chemical, and electron transmission attributes. The Co-Pi anchored to Ti3C2Tx in turn modifies the interlayer properties of MXene, prevents restacking of the layered MXene structure, provides additional electrocatalytic sites, and escalates the electrocatalytic efficiency. Cyclic voltammetry and potentiostatic electrolysis studies revealed a higher current response, lower reduction potential, and increased productivity at the Co-Pi/Ti3C2Tx/CFP electrode for benzyl chloride transformation with CO2 coupling, yielding the desired carboxylic acid. Under optimal conditions, potentiostatic electrolysis at ?1.6 V for 8 h yielded up to 62% PAA, following a diffusion-controlled two-electron reduction mechanism. Furthermore, the electrodes showed good repeatability, reproducibility of electrochemical responses, and excellent stability over 60 days. 2025 American Chemical Society -
Keggin-Type H5PMo10V2O40Intercalated MgAl-LDH: Structural Integrity and Bifunctional Electrocatalytic Activity
The development of earth-abundant electrocatalysts is central to sustainable water electrolysis, yet many systems are limited by poor electronic conductivity and inadequate durability. In particular, the high solubility of discrete polyoxometalates (POMs) clusters hinders their direct deployment as stable heterogeneous electrocatalysts. Here, a Keggin-type H5PMo10V2O40 POM is intercalated into MgAl layered double hydroxide (MgAl-LDH) by a formamide-assisted exfoliation-reassembly strategy to afford a POM@MgAl-LDH hybrid. Structural characterization confirms quantitative ion exchange of POM anions into the LDH galleries and an increase of the basal spacing to 9.210.5 Density functional theory calculations indicate thermodynamically favorable intercalation (?E ? ?2.3 eV per formula unit) and predict an equilibrium interlayer distance that matches the experiment. The hybrid exhibits a BET surface area of 50.6 m2 g1 and hierarchical porosity. In 1.0 M KOH, POM@MgAl-LDH functions as a bifunctional electrocatalyst, affording hydrogen and oxygen evolution overpotentials of 215 and 411 mV at 10 mA cm2, respectively, with ?97% current retention over 12 h of electrolysis. These results suggest that spatial confinement of redox-active POM clusters within an earth-abundant MgAl-LDH host reduces POM loss into solution and improves the electrocatalytic response of LDH framework, offering a practical route to nonprecious-metal bifunctional electrocatalysts for alkaline water splitting. 2026 American Chemical Society -
Buffer-Induced Electrocatalytic Hydrogen Evolution by a Cobalt Pentadentate Complex in Water
Elucidating proton transfer dynamics in water represents one of the most challenging problems in water splitting reactions due to the presence of multiple proton donors, which complicates the overall reaction kinetics. This study examines the impact of buffer pKa and its concentration on catalytic performance for hydrogen evolution catalyzed by a CoIII complex (1). The results demonstrate that buffer increases the catalytic rate of the hydrogen evolution reaction. This enhanced activity is supported by the number of buffer acids possessing varying pKa values, with 2-(N-morpholino)ethanesulfonic acid yielding the maximum catalytic current. A linear free energy relationship, a characteristic of a Brsted-type mechanism, is observed between the buffers pKa and catalytic rate constants. This substantiates that the rate-limiting step is controlled by the proton delivery mediated by the buffer acids. Moreover, the observed inhibition in catalytic activity at a higher concentration of buffer reveals the possible binding interaction between buffer and the cobalt center, thereby impeding substrate access. These findings underscore the critical role of buffer identity and its concentration in optimizing the proton-dependent catalytic reactions in water. 2026 American Chemical Society -
Utilizing Highly Reactive Lewis Pairs Generated by Oxygen Vacancies in the Cu3Mo2O9 Solid Catalyst for Cycloaddition of CO2 to 1,2-Propanediol
This work emphasizes generating highly reactive Lewis pair sites on CuMo oxides for CO2 activation and utilization in the cyclization reaction to produce propylene carbonate from 1,2-propanediol. The CuMo oxides were synthesized by enabling the oxygen vacancies that enhance the catalytically active sites, resulting in the formation of metastable cations (Mo5+ and Cu1+) and oxygen vacancies. Under ethanol-PEG-400 medium, the pure phase of Cu3Mo2O9 obtained at 500 C exposed maximum defects without any secondary phase compared to other screened catalysts. The experimental and theoretical investigations provide evidence for determining and correlating the characteristics of active sites with catalytic performance. The catalysts were extensively characterized along with density functional theory (DFT) studies, which revealed the presence of defect centers as one of the key factors in the enhanced activity. From the chemical bonding analysis, i.e., Crystal Orbital Hamiltonian Population (COHP) and Electron Localization Function (ELF), the CO2 molecule is known to form a strong chemisorption interaction with the catalyst surface that is facilitated by the oxygen vacancy/Lewis pairs. The Cu-Mo oxide catalyst achieved 99% conversion of 1,2-propanediol and 97% yield of propylene carbonate, outperforming previously reported catalysts. Thus, Cu-Mo oxide was shown to be highly efficient catalyst with good recyclability for 1,2-propanediol and the CO2 reaction. 2025 American Chemical Society.