Proton Supply Research Articles

Solvent Mediated Interfacial Microenvironment Design for High-Performance Electrochemical CO2 Reduction to C2+ Products.

Electrochemical CO2 reduction (CO2RR) in membrane electrode assembly (MEA) represents a viable strategy for converting CO2 into value-added multi-carbon (C2+) compounds. Therefore, the microstructure of the catalyst layer (CL) affects local gas transport, charge conduction, and proton supply at three-phase interfaces, which is significantly determined by the solvent environment. However, the microenvironment of the CLs and the mechanism of the solvent effect on C2+ selectivity remains elusive. Herein, a tailored interfacial structure is designed by introducing a solvent-mediated catalyst-ionomer-solvent microenvironment. The acetone surface promotion strategy is beneficial for the unfolded ionomers to uniformly coat the catalysts, which contributes to enhancing interfacial hydrophobicity and inhibiting hydrogen evolution. Furthermore, molecular dynamics (MD) simulation and in situ ATR-SEIRAS are employed to elucidate the appropriate interfacial network with a balanced distribution of CO2 and H2O. The uniform and continuous network in acetone is advantageous for CO2-to-C2+. The optimized structure favors the production of C2+ products in Cu-based MEA, exhibiting a high C2+ faradaic efficiency (FE) of 80.27% at 400mA cm-2.

Kinetically Accelerating Ni and C Dual Active Sites Via Pyrrolic-N for Water Dissociation and Alkaline Hydrogen Production

Green hydrogen, which is one of the most promising solutions to environmental issues and energy crises, can be produced through water electrolysis using renewable electricity as eco-friendly and sustainable route. However, the cathodic hydrogen evolution reaction (HER) has been a subject of extensive research due to the slow kinetics of proton-coupled electron transfer, which lowers the overall efficiency. In particular, the rate of HER in alkaline media appears two to three times slower than that in acidic or neutral media. This is because in order to form adsorbed hydrogen, additional water dissociation must first proceed in the Volmer step (H2O + e- → Had + OH-), followed by the coupling of adsorbed hydrogen in the Heyrovsky or Tafel steps (H2O + Had + e- → H2 + OH- / Had + Had → H2). The hydrogen adsorption-free energy (ΔGH*) has traditionally been considered the primary factor influencing the kinetics of the HER at the Heyrovsky and Tafel steps. However, it is important to note that sufficient proton supply to the catalytic sites relies on water adsorption capacity and the ability to cleave the HO-H bond. As a results, a proper strategy for achieving high hydrogen coverage (M-Had) must incorporate both water dissociation and hydrogen combination. Unfortunately, the activation of O- and H- containing intermediates for water dissociation and proton combination requires different catalytic properties, which highly presents a challenge. Therefore, it is crucial to understand the correlation between the catalytic chemical state, adsorption energy of intermediate species (H2O, OH, Had), and the kinetic mechanism of the HER from a theoretical standpoint.Pt-based materials are currently recognized as the most efficient catalysts for the HER. However, they exhibit unsatisfactory intrinsic kinetics under alkaline conditions due to the slow dissociation rate of water caused by the additional energy barrier of HO-H bond dissociation. Furthermore, their scarcity and high price limit their industrial applications. As an alternative, Ni-based materials are considered promising catalysts due to their Pt-like hydrogen adsorption-free energy and the possibility of optimizing water dissociation through chemical state modulation. Recent studies have shown that modulating the surface electronic structure of Ni-based materials through synergistic interactions is an effective way to activate intermediates for alkaline HER. However, most studies on chemical state reorganization focus on a single site, which underestimates the mechanism-based kinetics and makes it difficult to simultaneously control water dissociation and proton adsorption. Therefore, introducing dual active sites that optimize O- and H- affinity independently can be an effective strategy to reduce the energy barrier for Volmer, Heyrovsky and Tafel steps. Moreover, considering the proton pathway within Ni-based catalysts to accelerate alkaline HER kinetics, it is essential to simultaneously govern thermodynamics and kinetics through a kinetic-oriented design.In this study, we present a novel design approach that focuses on alkaline HER kinetics by incorporating dual active sites using Ni nanoparticles embedded in pyrrolic-N-rich carbon nanoplates (Ni@NCP), resulting in robust alkaline HER kinetics. The introduction of N-functional-rich polydopamine (PDA) serves two purposes: it ensures the uniform distribution of reduced Ni nanoparticles within the carbon substrate, and it enriches the ratio of pyrrolic-N in defective carbon, thereby regulating the properties of the Ni metal and the C atoms near the pyrrolic-N. Consequently, the Ni@NCP catalyst exhibits remarkable alkaline HER performance, with a low overpotential of 42 mV at a current density of 10 mA/cm2 and a Tafel slope of 94.9 mV/dec. These results outperform those of previously reported transition metal-based or single metal phase-based HER electrocatalysts. Further validation through the utilization of in-situ/operando Surface Enhanced Raman Spectroscopy (SERS), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations confirmed that the alkaline HER kinetics were significantly optimized by the pyrrolic-N-induced asymmetric electronic distribution, specifically by (ⅰ) shifting the d-band center (εd ) of the nearby Ni atoms towards the Fermi energy level to enhance the interaction with -H in H2O molecules and optimize the proton adsorption energy, (ⅱ) increasing the adsorption affinity of nearby C atoms towards H2O and -OH to optimize H2O adsorption, and (ⅲ) elongating the HO-H bonds, facilitating bond cleavage, and promoting simultaneous proton supply into Ni atoms. The kinetic-oriented design of dual active sites significantly reduces the kinetic energy barrier during Volmer step of water dissociation, resulting in facilitates the supply of sufficient protons for accelerated alkaline HER kinetics, ultimately enhancing the overall catalytic activity. Moreover, in a two-electrode system with Ni@NCP as the cathode for water electrolysis, Ni@NCP||IrO2 outperforms the commercial Pt/C||IrO2 system at the current density over 2.3 A/cm2, which shows superior potential for the practical application. Figure 1

The Effects of Water and Ion Management for Modulate CO2 Reduction Selectivity Via Anode Control

The process of conversion ethylene through carbon dioxide reduction reaction (CO2RR) shows potential in catalysis by encouraging the formation of C-C bonds while reducing the occurrence of competing reactions(1). Despite their potential, a deeper understanding of membrane electrode assembly (MEA) systems is needed due to their low selectivity. The MEA configuration, which eliminates the need for a catholyte, delivers humidified CO2 to the cathode, enhancing CO2 solubility and minimizing overall ohmic resistance by maintaining a narrow electrode gap, thus boosting energy efficiency(2). However, in MEA, since protons and ions from the anolyte for reaction are supplied to the catalyst through a membrane, additional understanding of the electrolyte supply effect is needed to optimize the overall system(3). Ions and water of electrolytes are essential for CO2RR. Water serves as a proton source for CO2RR and facilitates ion transport. However, the delicate balance of water is crucial in CO2RR systems. While water is necessary for proton supply, an excess of water at the cathode can lead to complications, particularly in promoting the competing hydrogen evolution reaction (HER)(4). HER can occur alongside CO2RR and consume protons and electrons, thereby reducing the selectivity of CO2 conversion and diminishing overall efficiency. Balancing the concentrations of ions and water is crucial for optimizing cell voltage and overall performance, highlighting the necessity of effective water and ion management approaches. While much research on water management has focused on cathodes, electrolytes, and membranes, the properties of the anodes have been relatively neglected. This study proposes the hypothesis that modulation of the anode electrode can have a significant impact on CO2RR performance. When comparing Ti-mesh, which facilitates the passage of electrolyte, with carbon paper, which restricts electrolyte movement, localized pH changes and optimal ethylene production efficiency were observed. In particular, in situ/operando analysis shows that under conditions of insufficient water and ion supply, local pH effects are promoted and Cu valence increases during CO2RR, resulting in optimal ethylene production efficiency at low current densities. However, at high current densities, the reaction was not evenly distributed and catalytic activity decreased. On the other hand, when water and ions are supplied smoothly, the ethylene production efficiency increases as the current density increases, showing that the material is sufficiently transferred. In addition, it was confirmed through the backside image that water crossed over to the cathode at the same time. This shows that the anode can affect the catalytic activity of the cathode side.Therefore, this study highlights the importance of effective ion and water management in improving CO2RR efficiency in MEA and highlights the central role of the anode in this process.References Zhan C, Dattila F, Rettenmaier C, Bergmann A, Kuhl S, Garcia-Muelas R, et al. Revealing the CO Coverage-Driven C-C Coupling Mechanism for Electrochemical CO(2) Reduction on Cu(2)O Nanocubes via Operando Raman Spectroscopy. ACS Catal. 2021;11(13):7694-701.Lee WH, Lim C, Lee SY, Chae KH, Choi CH, Lee U, et al. Highly selective and stackable electrode design for gaseous CO2 electroreduction to ethylene in a zero-gap configuration. Nano Energy. 2021;84.Choi W, Park S, Jung W, Won DH, Na J, Hwang YJ. Origin of Hydrogen Incorporated into Ethylene during Electrochemical CO2 Reduction in Membrane Electrode Assembly. ACS Energy Letters. 2022;7(3):939-45.Marcandalli G, Monteiro MCO, Goyal A, Koper MTM. Electrolyte Effects on CO(2) Electrochemical Reduction to CO. Acc Chem Res. 2022;55(14):1900-11. Figure 1

Enhanced photocatalytic synthesis of urea from co‐reduction of N2 and CO2 on Z‐schematic SrTiO3‐FeS‐CoWO4 heterostructure

The photocatalytic co‐reduction of CO2 and N2 is a sustainable method for urea synthesis under mild conditions. However, high‐yield synthesis of urea is a challenge due to the sluggish kinetics of the C‐N coupling reaction. Herein, we have successfully engineered a Z‐scheme photocatalyst, SrTiO3‐FeS‐CoWO4, for boosting photocatalytic urea synthesis via enhancing the initial CO2 and N2 adsorption step and reducing the energy barrier for the C‐N coupling reaction. A high urea yield of 8054.2 μg·gcat−1·h‐1 was achieved on SrTiO3‐FeS‐CoWO4, which was significantly higher than the state‐of‐the‐art. The SrTiO3‐FeS‐CoWO4 Z‐scheme photocatalyst, with accelerated charge transfer by FeS, not only had dual active sites for the chemical adsorption and activation of CO2 and N2, but also retained the high conduction band (‐1.50 eV) and accelerated supply of electrons and protons, which are responsible for its good photoreduction activity and significantly reduced energy barrier for the rate‐determining step of C‐N coupling reaction.

Enhanced Photocatalytic Synthesis of Urea from co-Reduction of N2 and CO2 on Z-Schematic SrTiO3-FeS-CoWO4 Heterostructure.

The photocatalytic co-reduction of CO2 and N2 is a sustainable method for urea synthesis under mild conditions. However, high-yield synthesis of urea is a challenge due to the sluggish kinetics of the C-N coupling reaction. Herein, we have successfully engineered a Z-scheme photocatalyst, SrTiO3-FeS-CoWO4, for boosting photocatalytic urea synthesis via enhancing the initial CO2 and N2 adsorption step and reducing the energy barrier for the C-N coupling reaction. A high urea yield of 8054.2 μg ⋅ gcat -1 ⋅ h-1 was achieved on SrTiO3-FeS-CoWO4, which was significantly higher than the state-of-the-art. The SrTiO3-FeS-CoWO4 Z-scheme photocatalyst, with accelerated charge transfer by FeS, not only had dual active sites for the chemical adsorption and activation of CO2 and N2, but also retained the high conduction band (-1.50 eV) and accelerated supply of electrons and protons, which are responsible for its good photoreduction activity and significantly reduced energy barrier for the rate-determining step of C-N coupling reaction.

NiO-Incorporated Cu/Cu2O Nanowires for Highly Efficient Electrochemical Nitrate Reduction to Ammonia.

Electrochemical nitrate reduction to ammonia (NRA) is a promising sustainable way to synthesize ammonia (NH3) from nitrate (NO3 -) contaminants. Cu-based electrocatalysts are frequently utilized for NRA due to their strong NO3 - adsorption and de-oxygenation ability. However, this kind of catalyst usually possesses the weak water dissociation ability, resulting in insufficient proton supply in alkaline media to retard the following hydrogenation step of O-containing intermediates (*NOx, typically NO2 -) to target NH3. Herein, NiO-incorporated Cu/Cu2O nanowires grown on nickel foam (p-CuNi@NF, p refers to plasma treatment) were synthesized via hydrothermal growth and subsequent O2 plasma treatment for efficient NRA electrocatalysis. On this p-CuNi@NF catalyst, NiO is able to accelerate the hydrogenation step by promoting the water dissociation to provide protons, ultimately facilitating efficient NRA. p-CuNi@NF exhibits excellent NH3 selectivity and yield in a wide potential range and reaches a high Faradaic efficiency (FENH3) of 97.5 % and a yield (YNH3) of 470 μmol h-1 cm-2 at -0.6 V, both of which largely surpass the Cu/Cu2O catalyst.

MXene quantum dots-Co(OH)2 heterojunction stimulated Co2+δ sites for boosted alkaline hydrogen evolution

Persevering structural stability of the active species after phase reconfiguration poses a key challenge for various sustainable catalytic systems. In this study, we construct a robust β-Co(OH)2 electrocatalyst via self-adaptive coordination of MXene quantum dots (MQDs) during phase transition from the Co2(OH)3Cl precursor to β-Co(OH)2 (MQDs/β-Co(OH)2/Co foam). The heterojunction induced the excellent electron transfer, causing the lattice strain of β-Co(OH)2, and the accumulated electrons at the MQDs end regulated the electronic density of Co sites (Co2+δ), reversing the structural instability of β-Co(OH)2 within the applied reduction potential range. Furthermore, density functional theory calculation confirms the role of well-matched heterogeneous interfaces in HER. The result shows the high-valance Co2+δ sites promote adsorption and dissociation of H2O, increasing proton supply and accelerating reaction rate. Concurrently, MQDs facilitate the adsorption of hydrogen intermediates and H2 generation. Our architected catalyst exhibited exceptional alkaline hydrogen evolution reactions (HERs) performance (91 mV@10 mA cm−2) and superior stability outperforms most reported β-Co(OH) 2-based catalysts. Our work demonstrates the efficacy of MQDs as co-catalysts in enhancing the activity and structural stability of catalysts.

Hydroxyl-enriched hydrous tin dioxide-coated BiVO4 with boosted photocatalytic H2O2 production

The rapid decomposition of H2O2 on the surface of inorganic photocatalyst (BiVO4) and insufficient proton supply from water leads to a low photosynthetic yield of H2O2. Herein, hydrous tin dioxide (HSnO) with massive hydroxyl groups was coated on the BiVO4 surface to greatly improve the photocatalytic H2O2 activity via simultaneous realization of providing sufficient protons and inhibiting H2O2 decomposition. After coating HSnO, Au nanoparticles as the O2-reduction active sites were selectively deposited on the (010) facet of BiVO4 to synthesize Au/BiVO4@HSnO photocatalyst. The resulting Au/BiVO4@HSnO photocatalyst exhibits excellent H2O2-production performance, in which the photogenerated H2O2 concentration (210.7 μmol L−1) is about 4.8 times higher than that of Au/BiVO4 after 2 h light irradiation in pure water. The outstanding photocatalytic performance can be attributed to simultaneous enhancement of H2O2 generation and the suppression of H2O2 decomposition by HSnO coating. Specifically, the HSnO coating with massive hydroxyl groups provides enough protons to promote the catalytic transformation of O2 into H2O2 on Au nanoparticles. More importantly, this coating not only allows water molecules to effectively permeate onto BiVO4 surface for rapid oxidation reaction, but also greatly inhibits the reverse reaction of H2O2 decomposition via decreasing its affinity with BiVO4 surface. This research offers new insights for boosting photocatalytic H2O2 production through surface coating strategy.

Facilitating photocatalytic CO2 methanation via synergetic feed of photon-induced carriers and reactants over S-scheme BiVO4@TiO2 nanograss/needle arrays

Herein, a unique structure BiVO4@TiO2 nanograss/needle arrays S-scheme heterojunction photocatalyst for CO2 photoreduction reaction was created. The photocatalyst can drive electrons to the reactive spots spontaneously and continuously, which effectively tackles the problem of severe recombination and disordered migration of photogenerated carriers. Theoretical calculations and experimental results demonstrate that adding BMIM-BF4 ionic liquid to generate BMIM-*CO2 intermediate promotes CO2 activation and enrichment of reactants concentration around the catalytic sites. Benefiting from the sufficient electron supply of catalytic sites and reinforced reactants supply in the interfacial microenvironment, the BiVO4@TiO2 photocatalyst shows high selectivity and activity of CO2-to-CH4 conversion. The CH4 selectivity increased to 57.3 % (132.7 μmol m-2h−1) and the methanation activity was increased by 8.6 times in the 5.0 % BMIM-BF4 aqueous solution. Significantly, the BiVO4@TiO2 NNAs catalyst obtains a solar-to-fuels energy efficiency of ∼ 0.46 ‰ under ultraviolet-enhanced light sources without any sacrificial agent or co-catalyst. This work displays the relationship between reaction process factors (electron supply, CO2 molecule, and proton supply) and CO2 photoreduction activity and selectivity, giving new insight into achieving efficient CO2 photoreduction conversion.

The Determinants of Supply Chain Performance in Manufacturing Industries: A Case Study of Proton Malaysia

This study examines the key elements that significantly impact supply chain performance in Proton Malaysia, a prominent participant in the automotive sector in Southeast Asia. The objective is to understand the impact of crucial factors on Proton's supply chain's performance, including information quality, information technology, information sharing, big data analytics capacity, supply chain integration, traceability, and agility. The study used a qualitative research methodology to examine Proton's supply chain dynamics, focussing on its strategic collaboration with Geely and the incorporation of new technology. Both primary and secondary data are utilized for analysis. The results demonstrate that Proton's focus on up-to-date information, sophisticated analysis, and robust supplier connections has greatly improved its ability to respond quickly and effectively to operational challenges and maintain its ability to recover from disruptions. Furthermore, the research emphasizes the significance of supply chain agility and integration in effectively responding to market fluctuations and reducing risks. The findings indicate that Proton must consistently engage in technology and supply chain innovation to retain its competitive advantage and successfully traverse the intricate nature of the global automobile market. These lessons apply to Proton and other manufacturing enterprises aiming to optimize their supply networks in a progressively dynamic and linked environment.

Merging semi-crystallization and multispecies iodine intercalation at photo-redox interfaces for dual high-value synthesis

The artificial photocatalytic synthesis based on graphitic carbon nitride (g-C3N4) for H2O2 production is evolving rapidly. However, the simultaneous production of high-value products at electron and hole sites remains a great challenge. Here, we use transformable potassium iodide to obtain semi-crystalline g-C3N4 integrated with the I-/I3- redox shuttle mediators for efficient generation of H2O2 and benzaldehyde. The system demonstrates a prominent catalytic efficiency, with a benzaldehyde yield of 0.78 mol g−1 h−1 and an H2O2 yield of 62.52 mmol g−1 h−1. Such a constructed system can achieve an impressive 96.25% catalytic selectivity for 2e- oxygen reduction, surpassing previously reported systems. The mechanism study reveals that the strong crystal electric field from iodized salt enhances photo-generated charge carrier separation. The I-/I3- redox mediators significantly boost charge migration and continuous electron and proton supply for dual-channel catalytic synthesis. This groundbreaking work in photocatalytic co-production opens neoteric avenues for high-value synthesis.

Proton‐Enriched Alginate–Graphene Hydrogel Microreactor for Enhanced Hydrogen Peroxide Photosynthesis

AbstractEfficient synthesis of H2O2 via photocatalytic oxygen reduction without sacrificial agents is challenging due to inadequate proton supply from water and difficulty in maintaining O−O bond during O2 activation. Herein, we developed a straightforward strategy involving a proton‐rich hydrogel cross‐linked by metal ions [M(n)], which is designed to facilitate the selective production of H2O2 through proton relay and metal ion‐assisted detachment of crucial intermediates. The hydrogel comprises CdS/graphene and alginate cross‐linked by metal ions via O=C−O−M(n) bonds. Efficient O2 reduction and hydrogenation occurred, benefitting from the collaboration between proton‐rich alginate and the photocatalytically active CdS/graphene. Meanwhile, the O=C−O−M(n) bonds enhance the electron density of α‐carbon sites on graphene, crucial for O2 activation and *OOH intermediate detachment, preventing deeper O−O bond cleavage. The role of metal ions in promoting *OOH desorption was demonstrated through Lewis acidity‐dependent activity, with Y(III) having the highest activity, followed by Lu(III), La(III), and Ca(II).

Proton-Enriched Alginate-Graphene Hydrogel Microreactor for Enhanced Hydrogen Peroxide Photosynthesis.

Efficient synthesis of H2O2 via photocatalytic oxygen reduction without sacrificial agents is challenging due to inadequate proton supply from water and difficulty in maintaining O-O bond during O2 activation. Herein, we developed a straightforward strategy involving a proton-rich hydrogel cross-linked by metal ions [M(n)], which is designed to facilitate the selective production of H2O2 through proton relay and metal ion-assisted detachment of crucial intermediates. The hydrogel comprises CdS/graphene and alginate cross-linked by metal ions via O=C-O-M(n) bonds. Efficient O2 reduction and hydrogenation occurred, benefitting from the collaboration between proton-rich alginate and the photocatalytically active CdS/graphene. Meanwhile, the O=C-O-M(n) bonds enhance the electron density of α-carbon sites on graphene, crucial for O2 activation and *OOH intermediate detachment, preventing deeper O-O bond cleavage. The role of metal ions in promoting *OOH desorption was demonstrated through Lewis acidity-dependent activity, with Y(III) having the highest activity, followed by Lu(III), La(III), and Ca(II).

Enhancing proton-coupled electron transfer drives efficient methanogenesis in anaerobic digestion

The enhancement of electron or proton transfer between syntrophic microbes has been widely recognised as a means for improving methane generation. However, the uncoupled supplementation of electrons and protons in multiphase anaerobic environment hinders the balanced uptake of electrons and protons in the cytoplasm of methanogens, limiting methanogenesis efficiency. Herein, the cooperative effect of a proton-conductive material (PM) and an electron-conductive material (EM) in enhancing proton-coupled electron transfer (PCET) and driving efficient methanogenesis in anaerobic digestion was investigated. The cooperation of the PM and EM significantly increased methane production and the maximum methane generation rate by 78.9 % and 103.5 %, respectively, indicating enhanced methanogenesis efficiency. Analysis of the physicochemical properties, biochemical components, and microbial dynamics revealed that the cooperation of the PM and EM improved the metabolism of syntrophic microbes, which was critically dependent on electron and proton transfer. This enhancement was primarily due to the improvement in PCET, as mainly supported by hydrogen/deuterium kinetic isotope effect measurements, multi-omics integration analyses and reaction thermodynamics and kinetics analyses. Our findings suggest that the PCET enhancement stimulated efficient membrane-bound enzymatic reactions related to electron-driven proton translocation and facilitated electron and proton supply for CO2 reduction to realise highly efficient methane generation. These findings are expected to provide a new insight into effective electron and proton coupling transfer for methanogenic metabolism in multiphase anaerobic environments.

Tandem Proton Transfer in Carboxylated Supramolecular Polymer for Highly Efficient Overall Photosynthesis of Hydrogen Peroxide.

Proton supply is as critical as O2 activation for artificial photosynthesis of hydrogen peroxide (H2O2) via two-electron oxygen reduction reaction (2e- ORR). However, proton release via water dissociation is frequently hindered because of the sluggish water oxidation reaction (WOR), extremely limiting the efficiency of photocatalytic H2O2 production. To tackle this challenge, carboxyl-enriched supramolecular polymer (perylene tetracarboxylic acid-PTCA) is elaborately prepared by molecular self-assembly for overall photosynthesis of H2O2. Interestingly, the interconversion between carboxyl as Brønsted acid and its conjugated base realizes rapid proton circulation. Through this efficient tandem proton transfer process, the spatial effect of photocatalytic reduction and oxidation reaction is greatly enhanced with reduced reaction barrier. This significantly facilitates 2e- photocatalytic ORR to synthesize H2O2 and in the meanwhile promotes 4e- photocatalytic WOR to evolve O2. Consequently, the as-developed PTCA exhibits a remarkable H2O2 yield of 185.6 μM h-1 in pure water and air atmosphere under visible light illumination. More impressively, an appreciable H2O2 yield of 78.6 μM h-1 can be well maintained in an anaerobic system owing to in situ O2 generation by 4e- photocatalytic WOR. Our study presents a novel concept for artificial photosynthesis of H2O2 via constructing efficient proton transfer pathway to enable rapid proton circulation.

Tandem Proton Transfer in Carboxylated Supramolecular Polymer for Highly Efficient Overall Photosynthesis of Hydrogen Peroxide

AbstractProton supply is as critical as O2 activation for artificial photosynthesis of hydrogen peroxide (H2O2) via two‐electron oxygen reduction reaction (2e− ORR). However, proton release via water dissociation is frequently hindered because of the sluggish water oxidation reaction (WOR), extremely limiting the efficiency of photocatalytic H2O2 production. To tackle this challenge, carboxyl‐enriched supramolecular polymer (perylene tetracarboxylic acid—PTCA) is elaborately prepared by molecular self‐assembly for overall photosynthesis of H2O2. Interestingly, the interconversion between carboxyl as Brønsted acid and its conjugated base realizes rapid proton circulation. Through this efficient tandem proton transfer process, the spatial effect of photocatalytic reduction and oxidation reaction is greatly enhanced with reduced reaction barrier. This significantly facilitates 2e− photocatalytic ORR to synthesize H2O2 and in the meanwhile promotes 4e− photocatalytic WOR to evolve O2. Consequently, the as‐developed PTCA exhibits a remarkable H2O2 yield of 185.6 μM h−1 in pure water and air atmosphere under visible light illumination. More impressively, an appreciable H2O2 yield of 78.6 μM h−1 can be well maintained in an anaerobic system owing to in situ O2 generation by 4e− photocatalytic WOR. Our study presents a novel concept for artificial photosynthesis of H2O2 via constructing efficient proton transfer pathway to enable rapid proton circulation.

Surficial Reconstruction of Pt-Ni/NiS and Its Effect on Electrocatalytic Hydrogen Evolution in Alkaline Medium.

Cyclic voltammetry pretreatment of Pt-based electrocatalysts has been proven to be a normal activation process on achieving the optimal alkaline hydrogen evolution performance. Until now, the congruent relationship between the microstructural evolution and performance improvement during this process has rarely been reported. Herein, when the in situ transmission electron microscopy and in situ Raman analyses are employed, a self-reconstruction process from crystalline NiS into amorphous nickel hydroxide hydrate [Ni(OH)2-x·H2O, where x ≈ 0.3] on the surface of platinum-nickel nanowires has first been captured, which is the critical water dissociation active site to offer a sufficient proton supply. Furthermore, such a surficial reconstruction triggers an increase in the current density from -2.3 to -38.8 mA/cm2 (at -70 mV), which is nearly 17 times. These observations point to the fact that it is essential to consider the fundamental mechanisms of hydrogen evolution on the active sites when the process is scaled up.

Enhanced photocatalytic CO2 conversion into reusable fuels with efficient solid-state proton donors

Lead halide perovskites driven photocatalytic CO2 reduction reaction (CO2RR) is restricted by H2O proton source due to the poor water-resistance of perovskites and difficult dissociation of H2O molecules. In this paper, a novel solid-state proton donor of amino acid modified melamine foam (Ami-MF) is developed, which could improve CO2RR of CsPbBr3/Bi2WO6 S-scheme heterojunction. On the one hand, amino acid molecules possess abundant –COOH and –NH2 groups, which are broken easily by catalyst oxidation compared with H2O, supplying sufficient protons for CO2RR. Product yield of Glu-MF/CsPbBr3/Bi2WO6 reaches 112.81 μmol/g/h, which is 3.8 times higher than that (29.83 μmol/g/h) of H2O-MF/CsPbBr3/Bi2WO6. Moreover, glutamic acid (Glu), cysteine (Cys), arginine (Arg) as typical acidic, neutral and basic amino acids are selected to explore proton supply from different amino acids. Glu-MF/CsPbBr3/Bi2WO6 exhibits the best CO2RR than other two Ami-MF, ascribing to the dicarboxylic structure of Glu. On the other hand, MF is an integral part in solid-state proton donor. Product yield of Glu-MF/CsPbBr3/Bi2WO6 is about 46.2 times higher than that (2.44 μmol/g/h) of powdery Glu/CsPbBr3/Bi2WO6, which ascribes to the efficient gas–solid CO2RR system induced by the three-dimensionality and porosity of MF. This study develops an efficient solid proton donor to enhance perovskites driven CO2RR.

Defect-Mediated Cu–S Pair Active Sites Modulating Proton Supply to Facilitate Overall CO2 Photoreduction with H2O

Defect-Mediated Cu–S Pair Active Sites Modulating Proton Supply to Facilitate Overall CO₂ Photoreduction with H₂O

Transition-Metal Porphyrin-Based MOFs In Situ-Derived Hybrid Catalysts for Electrocatalytic CO2 Reduction.

Excellent electrocatalytic CO2 reduction reaction activity has been demonstrated by transition metals and nitrogen-codoped carbon (M-N-C) catalysts, especially for transition-metal porphyrin (MTPP)-based catalysts. In this work, we propose to use one-step low-temperature pyrolysis of the isostructural MTPP-based metal-organic frameworks (MOFs) and electrochemical in situ reduction strategies to obtain a series of hybrid catalysts of Co nanoparticles (Co NPs) and MTPP, named Co NPs/MTPP (M = Fe, Co, and Ni). The in situ introduction of Co NPs can efficiently enhance the electrocatalytic ability of MTPP (M = Fe, Co, and Ni) to convert CO2 to CO, particularly for FeTPP. Co NPs/FeTPP endowed a high CO faradaic efficiency (FECOmax = 95.5%) in the H cell, and the FECO > 90.0% is in the broad potential range of -0.72 to -1.22 VRHE. In addition, the Co NPs/FeTPP achieved 145.4 mA cm-2 at a lower potential of -0.70 VRHE with an FECO of 94.7%, and the CO partial currents increased quickly to reach 202.2 mA cm-2 at -0.80 VRHE with an FECO of 91.6% in the flow cell. It is confirmed that Co NPs are necessary for hybrid catalysts to get superior electrocatalytic activity; Co NPs also can accelerate H2O dissociation and boost the proton supply capacity to hasten the proton-coupled electron-transfer process, effectively adjusting the adsorption strength of the reaction intermediates.