Water Splitting Reaction Research Articles

Photocatalytic Hydrogen-Future Energy

The rapid increase in energy consumption, driven by the rising vehicle population and travel demand, has led to a surge in greenhouse gas (GHG) emissions. This necessitates the development of sustainable and eco-friendly technologies and fuels to mitigate global and local environmental impacts. Four primary justifications support transitioning to alternative fuels and technologies: dwindling oil reserves worldwide, adverse environmental effects of vehicle pollution, escalating oil production costs, and the complex challenges of maintaining energy security in international markets. To address these concerns, there is a growing global demand for hydrogen as a sustainable energy source. Utilizing photocatalytic and photoelectrochemical (PEC) water-splitting reactions, particularly with graphene quantum dots-based composites, offers promising avenues for efficient and eco-friendly hydrogen generation. The selection of these systems is based on their unique physical and chemical properties, with graphene providing strong support and efficient electron transport, while components like cadmium sulfide (CdS) and zinc oxide (ZnO) enhance light absorption and charge separation. This integrated approach shows potential for efficient and sustainable hydrogen production, further bolstered by advances in metal-containing photocatalysts and collaborative efforts across energy markets.

Bagasse derived N-doped graphitic carbon encapsulated cobalt nanoparticles as an efficient bifunctional catalyst for water splitting reactions

The utilization of non-precious metal-based electrodes to unlock cost-effective and scalable processes for the production of clean energy is highly desirable. Herein, we reported a straightforward hydrothermal carbonization method for the synthesize of nitrogen-doped graphitic carbons integrated with cobalt (Co@NGC-600, Co@NGC-700, and Co@NGC-800) from sugarcane bagasse and their electrocatalytic applications in oxygen and hydrogen evolution reactions. The graphitic nature of the Co integrated N-doped carbon materials was confirmed by Raman and XPS analysis. FESEM and HRTEM analysis confirms the dispersion of Co on N-doped carbon nanosheets. The Co@NGC-800 catalyst shows low overpotential and Tafel slope, requiring only 304 mV (84.1 mV dec−1) for oxygen electrode and 234 mV (118 mV dec−1) for HER at a current density of 10 mA cm−2. Moreover, Co@NGC-800 materials showed better activity than Co@NGC-700, Co Co@NGC-600, and Co@NC. The active Co@NGC-800 bifunctional electrocatalysts pair contributes to the fabrication of a water electrolyser with a 10 mA/cm2 current density at 1.68 V. The Co@NGC-800 // Co@NGC-800 electrocatalyst exhibits good stability over a period of 24 h with negligible potential aberration during the process of water splitting. The electrocatalytic performance of the prepared catalyst in a 1.0 M KOH solution exhibits admirable bifunctional activity and remarkable stability. In fact, it outperforms cobalt-based and carbon-supported electrocatalysts, including highly valued commercial catalysts like IrO2 and Pt@C. The solar cell configuration, utilizing the energetic bifunctional Co@NGC-800 electrocatalyst, can continuously generate hydrogen and oxygen. The overall water-splitting process of Co@NGC-800 catalyst delivered at a cell voltage of 1.68 V, enabling sustained and efficient oxygen and hydrogen evolution at a large scale.

Perovskite-type samarium iron oxide adorned on reduced graphene oxide composite: A high-performance electrocatalyst for OER

The oxygen evolution process (OER), an essential and necessary reaction in water splitting to produce clean hydrogen fuel were investigated using a number of electrocatalysts. Non-noble metal catalysts are increasingly being used in place of noble metal catalysts because of their unique qualities, which include affordability, environmental friendliness and electrocatalytic activity. In this work, SmFeO3/rGO composite is prepared for an anion exchange reaction, which is used as catalyst on nickel foam in 1.00 M KOH electrolyte for OER. The fabricated electrocatalysts were confirmed by X-ray powder diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray (EDX) spectroscopy and scanning electron microscopy (SEM). The BET determined surface area of SmFeO3/rGO composite is 51 cm2/g which is better for OER activity. The distinct structure of the nanocomposite displays increased surface area, increasing active sites with plentiful potential for charge transfer and prolonging the material's life. The electrochemical results represented that composite had lower overpotential (180 mV) with Tafel slope (34 mV/dec), displaying higher charge transfer during OER showing efficient electrocatalytic activity and high reliability of 55h. The reasons for lower overpotential and lower Tafel slope values were increased surface area and enhanced number of active spots in composite and also due to presence of non-kinetic effects that alter the Tafel slope values. The electrocatalyst may be able to facilitate the oxidation reaction based on all of these qualities. As a consequence, created composite reacts with outstanding efficacy for the OER process and energy conversion applications.

One-pot synthesis of NiCe-LDH for efficient electrochemical water splitting: A comprehensive experimental and theoretical study

The electrochemical splitting of water is a cost-effective and convenient way to generate H2 gas, utilizing readily available and affordable electrocatalysts. In the present report, a bimetallic LDH consisting of Ni and Ce (NiCe-LDH) was prepared via a very simple solvothermal method for the first time. The results showed that the solvothermal method produced NiCe-LDH nanoflakes with excellent potential for water electrolysis. The investigations found that the NC-2:1/NF sample had low overpotential of 110 mV with Tafel slope of 54.6 mV dec−1 in HER, while the NC-3:2/NF sample had low overpotential of 212 mV with Tafel slopes of 67.5 mV dec−1 in OER. Moreover, NiCe-LDH with NC-2:1 as a cathode and NC-3:2 as an anode provided a low cell voltage of 1.50 V at 10 mA cm−2 for the overall water-splitting reaction. Furthermore, a detailed theoretical investigation using DFT calculations was carried out to clear the mechanism of water electrolysis.

Amorphous and crystalline heterostructure MoSe2/NiFe-LDH through p-n junction formation for electrochemical water splitting-synergistic back bonding effect

Designing a long-lasting, highly effective, non-noble metal-free electrocatalyst for both hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is a strenuous task for water electrolysis. Here, in our study, an ordered NiFe-layer double hydroxide (LDH)/MoSe2 as p-n junction material was designed using facile two-step hydrothermal process for the overall water splitting reaction. Additionally, synthesized NiFe-LDH/MoSe2, electrode exhibits long-term durability in both acidic and alkaline medium for HER and OER, respectively. Mott-Schottky experiments provides the insights of interfacial electron transfer, where the electron is transported from n-type NiFe-LDH to p-type MoSe2, resulting in the generation of the p-n junction in MoSe2/NiFe-LDH. As the formation LDH and transition dichalcogenides p-n junction leads to activation of the catalysts towards the OH− adsorption that may enable the water electrolysis with a low overpotential. The XPS analysis supports the electron transfer from Fe to Mo resulting in the formation synergistic back bonding between the p-n heterojunction. This strategy opens up an alternative path to a highly effective, relatively low-price catalyst for the global production of renewable energy fuels.

Wireless Light-Emitting Electrode Arrays for the Evaluation of Electrocatalytic Activity.

Water splitting has become a sustainable and clean alternative for hydrogen production. Commonly, the efficiency of such reactions is intimately related to the physico-chemical properties of the catalysts that constitute the electrolyzer. Thus, the development of simple and fast methods to evaluate the electrocatalytic efficiency of an electrolyzer is highly required. In this work, we present an unconventional method based on the combination of bipolar electrochemistry and light-emitting diodes, which allows the evaluation of the electrocatalytic performance of the two types of catalysts, composing an electrolyzer, namely for oxygen and hydrogen evolution reactions, respectively. The integrated light emission of the diode acts as an optical readout of the electrocatalytic information, which simultaneously depends on the composition of the anode and the cathode. The electrocatalytic activity of Au, Pt, and Ni electrodes, connected to the LED in multiple anode/cathode configurations, towards the water splitting reactions has been evaluated. The efficiency of the electrolyzer can be represented in terms of the onset electric field (ϵonset) for light emission, obtaining variations that are in agreement with data reported with conventional electrochemistry. This work introduces a straightforward method for evaluating electrocatalysts and underscores the importance of material characterization in developing efficient electrolyzers for hydrogen production.

Electrochemical deposition of nickel sulfide catalysts on commercial carbon rods as low-cost electrodes for hydrogen generation

Nowadays, the challenge of the world and the scientific community is to find and effectively use renewable energy sources. One of the renewable energy research subjects that has been hotly discussed recently is the water-splitting reaction to produce hydrogen. In this study, we focus on fabricating nickel sulfide (NiS) materials deposited on commercial carbon rod (CR) substrates and using them as electrodes for the electrochemical water-splitting reaction to produce hydrogen gas. In detail, NiS materials were decorated on commercial carbon rods (NiS/CR) by cyclic voltammetry electrochemical deposition with a potential range from 0.2 to −1.2 V (versus Ag/AgCl), a scan rate of 10 mV s−1, and 15 cycles. Benefiting a strong interfacial synergetic effect based on NiS/CR materials shows an excellent electrocatalytic activity for hydrogen evolution reaction (HER). Specifically, the NiS/CR electrode exhibits a high performance with low overpotential (70 mV for HER) and a slight Tafel slope (50 mV dec−1). Besides, annealing temperature helps increase the crystal properties, causing the appearance of NiS2 and Ni3S2 phases in NiS/CR@400 samples. Interestingly, the electrochemical surface area (ESCA) of the NiS/CR@400 sample significantly increased (17.3%) compared to the NiS/CR sample (5.8% of the total physical surface area) is due to the presence of NiS2 and Ni3S2, leading to NiS/CR@400 sample enhances the active sites by 16.0 mF cm−2. Furthermore, the long-term durability of NiS/CR@400 electrodes is good electrocatalytic over a continuous cycling 12-hour operation at 20 mA cm−2 in an alkaline environment. The NiS/CR is a promising electrode candidate for high HER performance, and here is a new design of electrocatalysts for water splitting.

Superiority of CuSe as a non-nobel electrocatalyst among copper chalcogens for overall water splitting reactions

Among the transition metals copper is one of the cheapest earth- abandoned elements which can enhance electrocatalytic activity. The Cu-based catalysts are superior for catalytic performance and stability in alkaline media for oxygen evolution reaction (OER) and exhibit high activity in acidic media for hydrogen evolution reaction (HER).Synthesized CuSe nanoparticle is found as the most efficient bifunctional electrocatalyst among the synthesized Cu chalcogenides for water splitting reaction. Electrocatalytic performance for water oxidation was investigated in alkaline solution1(M) KOH for OER and 0.5 (M) H2SO4 for HER. To achieve 10 mA/cm2, it was observed an over potential (mV) of 343 for OER and 126 for HER, which are much smaller than these of CuS (385,320) and CuO (410, 345) studied. In this article, we have elucidated some essential criteria need to be specified to evaluate the water splitting performance including onset potential, overpotential, Tafel slope, turnover frequency (TOF), and stability of the copper chalcogenide nanoparticles.

Enhanced photocatalytic performance of MXene-Modified cation-exchanged CoFe-LDH/CoFeCrO4 heterostructure for Antibiotic degradation and hydrogen production through synergistic charge dynamics

Systemizing an effective charge-transfer channel across a junction interface replete with ample active sites for enhancing the photocatalytic activity of semiconducting materials presents a formidable challenge. Here, we present a novel approach based on an in situ hydrothermal method for synthesizing CoFe-Layered Double Hydroxide (LDH)/CoFeCrO4 heterojunction materials that were partially derived from CoFe-LDH. These materials synergistically interact with Ti3C2 MXene nanosheets facilitating multi-interface interactions. Indeed, the highest tetracycline hydrochloride degradation rate of nearly 92% in 2 h was achieved because of the intense synergy between the CoFe-LDH/CoFeCrO4 heterojunction material optimized with 7.5 wt% of MXene nanosheets (CMC-7.5). This degradation performance was 3.1 times greater than that of the original CoFe-LDH. Further, CMC-7.5 produces the highest H2 gas of 458.79 μmol h−1g−1 from a photocatalytic water splitting reaction. The formation of a Schottky energy barrier between the partially derived CoFe-LDH/CoFeCrO4 unit and MXene promoted the fast transfer of photogenerated electrons from CoFe-LDH/CoFeCrO4 to the surface of MXene, thereby providing a plethora of active sites for photocatalytic reactions. Photoelectrochemical assessments using transient and linear sweep voltammetry along with electrochemical impedance spectroscopy confirmed efficient charge carrier transfer. Moreover, the optimized CMC-7.5 photoelectrode has a superior integral area and exhibited excellent stability over 100 cycles. Finally, the study outlines the construction of several advanced materials with multi-interface heterojunctions involving cation-exchanged LDH derivatives with high photogenerated charge carrier separation efficiency and minimal interfacial migration resistance to serve as stability benchmarks for practical applications.

Active-learning for global optimization of Ni-Ceria nanoparticles: The case of Ce4-xNixO8- x (x = 1, 2, 3).

Ni-CeO2 nanoparticles (NPs) are promising nanocatalysts for water splitting and water gas shift reactions due to the ability of ceria to temporarily donate oxygen to the catalytic reaction and accept oxygen after the reaction is completed. Therefore, elucidating how different properties of the Ni-Ceria NPs relate to the activity and selectivity of the catalytic reaction, is of crucial importance for the development of novel catalysts. In this work the active learning (AL) method based on machine learning regression and its uncertainty is used for the global optimization of Ce(4-x)NixO(8-x) (x = 1, 2, 3) nanoparticles, employing density functional theory calculations. Additionally, further investigation of the NPs by mass-scaled parallel-tempering Born-Oppenheimer molecular dynamics resulted in the same putative global minimum structures found by AL, demonstrating the robustness of our AL search to learn from small datasets and assist in the global optimization of complex electronic structure systems.

A Mini Review on Borate Photocatalysts for Water Decomposition: Synthesis, Structure, and Further Challenges.

The development of novel photocatalysts, both visible and UV-responsive, for water decomposition reactions is of great importance. Here we focused on the application of the borates as photocatalysts in water decomposition reactions, including water splitting reaction, hydrogen evolution half-reaction, and oxygen evolution half-reaction. In addition, the rates of photocatalytic hydrogen evolution and oxygen evolution by these borate photocatalysts in different water decomposition reactions were summarized. Further, the review summarized the synthetic chemistry and structural features of existing borate photocatalysts for water decomposition reactions. Synthetic chemistry mainly includes high-temperature solid-state method, sol-gel method, precipitation method, hydrothermal method, boric acid flux method, and high-pressure method. Next, we summarized the crystal structures of the borate photocatalysts, with a particular focus on the form of the B-O unit and metal-oxygen polyhedral in the borates, and used this to classify borate photocatalysts, which are rarely mentioned in the current photocatalysis literature. Finally, we analyzed the relationship between the structural features of the borate photocatalysts and photocatalytic performance to discuss the further challenges faced by the borate photocatalysts for water decomposition reactions.

High performance NaNbO3/CdS/Bi2S3 ternary heterostructured photoelectrocatalysts for efficient OER activity

CdS and Bi2S3 decorated NaNbO3 samples were prepared by hydrothermal and linker assisted combinatory approach using oleic acid and starch as surface capping agents. Successful deposition of small sized and high surface area CdS and Bi2S3 over the smooth surface of large sized NaNbO3 was carried out. To prepare heterostructures of NaNbO3 different weight ratios of CdS and Bi2S3 were employed. The as-prepared heterostructures were subsequently characterized by X-ray diffraction (XRD), UV–visible diffused reflectance spectroscopy (DRS), Field Emission Scanning Electron Microscopy (FESEM), Brauner-Emmette-Teller (BET) surface area studies, and X-ray Photoelectron spectroscopy (XPS) studies. As-developed heterostructures were investigated as photoelectrocatalysts (PEC) for oxygen evolution reaction (OER) from water splitting reaction. From PEC OER investigations, it was observed that heterostructured sample (HS-2) with 10 wt % CdS and 5 wt% Bi2S3 show efficient and enhanced PEC OER activity as compared to the pristine parent compounds. The maximum current density of 11.9 mA/cm2 with low onset potential of 0.89 V and low tafel slope of 107 mV/day was observed in HS-2 sample under white light illumination. The efficient and enhanced activity was attributed to red shift in the absorption of NaNbO3 sample and efficient charge separation taking place due to deposition of CdS and Bi2S3 over the surface of NaNbO3.

Construction of mesoporous Ni-Co-Mo oxide/sulfide composite composite nanosheet arrays as bifunctional material for charge storage and oxygen evolution reaction applications

At present, energy conversion and energy storage devices are gradually integrated together, which puts forward higher requirements for the design and construction of electrode materials. Herein, bi-functional Co-Mo oxides and Ni/Co sulfides (NCMOS) composite nanosheet arrays on Ni foam are constructed for supercapacitors and oxygen evolution reaction (OER) of water splitting. The Ni-Co-Mo nanosheet precursor is firstly synthesized by stepwise hydrothermal processes and then converted into Ni-Co sulfide and Co-Mo oxide by in-situ sulfurization. The nanoarray and in-situ sulfurization of active materials bring more reactive active sites, optimize reaction kinetics, and shorten the transport path of electrons and charges, which enhance energy storage performance and OER catalytic activity of NCMOS material. In terms of supercapacitor applications, NCMOS exhibits high specific capacity (1332.1 C g–1) and good cycle stability. For OER application, NiCMOS shows lower OER overpotential (290 mV at 100 mA cm–2), smaller Tafel slope (87.2 mV dec–1) and excellent catalytic stability in oxygen evolution for 60 h. The excellent charge storage and OER properties suggest that bi-functional oxide/sulfide composites have great potential in energy conversion and storage-integrated devices.

Hydrogen generation via water splitting with hexagonal silicon monolayers as (photo)catalysts

Here, we explore the possibility of using pristine hexagonal silicon (hex‑Si) monolayers as (photo)catalysts for water splitting. We found that pristine hex‑Si monolayers show promise as H2O activation site, promoting oxygen evolution reaction (OER), and energetically favorable O2 production in both acidic and alkaline media. However, hydrogen evolution reaction (HER) and OER on this surface do require a substantial overpotential due to the weak bond between H2O and the pristine hex‑Si monolayer, strong H and OH adsorption on the hex‑Si surface, and the energy needed for OOH binding in both acidic and alkaline conditions. Understanding these findings aids in developing hex‑Si-based (photo)catalysts for future water splitting reactions.

The effect of electrostatically enhanced adsorption of polylysine on a heterogeneous cation-exchange membrane

Electrostatics influences the interactions between charged biopolymers and ion-exchange membranes. When carrying a charge opposite to that bound in the membrane, the biopolymers readily adsorb on the membrane surface, altering local conditions and, thus, affecting the desalination processes that proceed. To provide a coherent description of the consequences of such adsorption, we experimentally investigate the effects of polylysine as a model cationic polymer on the behavior of a heterogenous cation-exchange membrane. We show that even short exposure to polylysine changes the membrane behavior dramatically. Such a change reflects the influence of the adsorbed polylysine on natural convection, electroconvection, and water splitting. By directly observing the membrane-electrolyte interface, we find polylysine suppresses the beneficial electrical-field-induced convective transport at the membrane-electrolyte interface. Specifically, it diminishes electroconvection dominating at the membrane surface for polylysine-free solutions and attenuates natural convection, dictating the developed flow patterns. At the same time, it provides conditions enhancing a water-splitting reaction, significantly affecting the pH of the solutions adjacent to the membrane. All these effects are dependent on the polylysine concentration. Our study emphasizes the potentially harmful impact of biomolecular adsorption mediated by electrostatic interactions.

Theoretical inspection of high-efficiency single-atom catalysts based on π-π conjugated holey graphitic g-C7N3 monolayer: Marvelous water-splitting and oxygen reduction reactions activities

Hydrogen evolution reaction (HER) and oxygen evolution/reduction reaction (OER/ORR) relying on high-performance and low-cost single-atom catalysts (SACs) driven by renewable energy sources offer a sustainable route to carbon-neutral chemicals and fuels. Herein, first-principles calculations were performed to investigate the catalytic HER/OER/ORR activity of a novel graphitic carbon nitride monolayer (g-C7N3) supported single transition metal (TM@g-C7N3). High stability as well as positively charged active site (TM-site) and desirable electrical conductivity lay the foundation for TM@g-C7N3 acting as efficient HER/OER/ORR electrocatalysts. We screened out the non-noble-metal Rh@g-C7N3 SAC exhibiting great potential as the trifunctional electrocatalysts for water splitting (ηHER= 0.06 V and ηOER= 0.46 V) and a metal-air battery (ηORR= 0.28 V) on both kinetic and thermodynamic scales, whereas the Ni@g-C7N3 can be served as a bifunctional OER/ORR catalyst with a low overpotential of 0.33 V/0.31 V, for both of which the high thermodynamic stability and oxidation barrier guarantee their outstanding performances at ambient conditions. The mechanism analysis indicates the filling of d-orbital electrons of TM-atom can play an important role in determining the value of an energy descriptor (ΔGOH*), and the suitable ΔGOH* values make for the TM@g-C7N3 candidates to possess favorable OER/ORR overpotential. Particularly, the Rh-d orbital of Rh@g-C7N3 is evidently hybridized with the OH*-p orbital, resulting in the lone electrons initially distributed in the antibonding orbital pairing up and occupying the downward bonding orbital, ensuring OH* can be adsorbed on Rh@g-C7N3 appropriately. Moreover, multiple-level descriptors including d-band center, COHP, Nd, and φ are used to reveal the origin of the electrocatalytic activity.

Enhanced photoelectrochemical water splitting via 3D flow field structure: Unveiling the decisive role of interfacial mass transfer

The efficiency of photoelectrochemical water splitting is not only related to the electrode material, but also influenced by the mass transport at the electrode surface. Here, we design a novel photoelectrochemical water splitting reactor, which generates a turbulent flow (0–145 mL/min) at the electrode/electrolyte interface. It was revealed that the reactor has a significant effect on the electrolyte flow, and the flow rate on the photocurrent density was more significant during the transition period of the flow state and the high flow rate. The 3D flow field structure improved the water splitting reaction of TiO2 photoelectrode by 130% at the flow rate of 130 mL/min, and consequently, the TiO2 exhibited a photocurrent density of 0.142 mA·cm−2 at 1.23 V versus the reversible hydrogen electrode. Then we changed the temperature (20–90 °C) of the electrolyte, and electrochemical impedance spectra results indicated that the ion transport impedance decreased with increasing electrolyte temperature in the experimental range. The photocurrent density increased by about 2.2 times at 90 °C compared to that at 20 °C. This work provided insights of the structure design on the photoelectrode/electrolyte interface in solar water splitting and revealed the non-negligible effect of interfacial mass transport in photoelectrochemical performance.

FeCoNiMgB high-entropy boride powder with a fluffy cotton structure and enhanced activity in the oxygen evolution reaction

Exploring efficient, low-cost electrocatalysts is critical for improving the efficiency of water splitting reactions. Noble-metal-based oxides exhibit high activities in the oxygen evolution reaction (OER). However, their high cost and the lack of natural resources hinder their practical application. Therefore, in this study, we successfully synthesized an FeCoNiMgB high-entropy boride powder via a facile chemical reduction method for use as an OER catalyst in an alkaline medium. The FeCoNiMgB powder, with an ultrathin fluffy cotton structure, exhibited an excellent OER catalytic performance, affording an overpotential of 268 mV at a current density of 10 mA/cm2 and a low Tafel slope of 42.9 mV/dec; this performance was superior to those of FeCoNiB, FeNiMgB, CoNiMgB, FeCoMgB, and commercial RuO2. The FeCoNiMgB powder also displayed remarkably stable catalytic properties for >72 h with no clear evidence of degradation. Finally, using theoretical calculations, the excellent OER performance of FeCoNiMgB was verified in terms of its adsorption and charge transfer energies and covalence. The performance and stability of FeCoNiMgB were equivalent or superior to those of several nanostructured catalysts, and thus, this study provided valuable insight into the design of efficient high-entropy boride materials.

Catalyst self-assembly accelerates bimetallic light-driven electrocatalytic H2 evolution in water.

Hydrogen evolution is an important fuel-generating reaction that has been subject to mechanistic debate about the roles of monometallic and bimetallic pathways. The molecular iridium catalysts in this study undergo photoelectrochemical dihydrogen (H2) evolution via a bimolecular mechanism, providing an opportunity to understand the factors that promote bimetallic H-H coupling. Covalently tethered diiridium catalysts evolve H2 from neutral water faster than monometallic catalysts, even at lower overpotential. The unexpected origin of this improvement is non-covalent supramolecular self-assembly into nanoscale aggregates that efficiently harvest light and form H-H bonds. Monometallic catalysts containing long-chain alkane substituents leverage the self-assembly to evolve H2 from neutral water at low overpotential and with rates close to the expected maximum for this light-driven water splitting reaction. Design parameters for holding multiple catalytic sites in close proximity and tuning catalyst microenvironments emerge from this work.

High DHA selectivity and low-cost electrode for glycerol oxidation: CuO regulates MnO2 electron density to promote DHA desorption

Glycerol oxidation reaction (GOR) is an attractive alternative reaction for oxygen evolution reaction (OER) in the electrochemical water splitting and can be used to generate high-value products. However, the development of GOR electrocatalysts with high catalytic activity and low cost is challenging. In this research, a self-supported copper-manganese electrode (MnO2-CuO/CF) was developed, which attains a current density of 10.7 mA cm−2 at a low potential of 1.3 V, while yielding 1,3-dihydroxyacetone (DHA), with a selectivity of 60%. DFT calculations reveal the synergistic effect between CuO and MnO2, enhancing glycerol adsorption. Additionally, the overlap configuration of CuO and MnO2 results in a lower electron density on MnO2, preventing further oxidation and increasing DHA selectivity. By coupling GOR and water electrolysis, the dual output of high value-added organic products and high-purity hydrogen can be realized, which provides a new idea for green hydrogen production and electrochemical synthesis of high value-added chemicals.