Application In Water Splitting Research Articles

MnO2 anchored N–Ti3C2 MXene as a bifunctional electrode for enhanced water splitting

The domain of energy research is vigorously exploring a wide array of materials, from advanced carbon-based substances like graphene and carbon nanotubes to emerging contenders like MXenes. Ti3C2 MXene offers exceptional performance in electrochemistry, benefiting from its remarkable electronic conductivity, considerable surface area, chemical stability, cost-effectiveness, hydrophilicity, and eco-friendliness. However, it undergoes self-accumulation, which diminishes the number of electrochemically active sites, resulting in decreased performance. In this study, MnO2 particles are intricately anchored onto the surfaces and within the layers of nitrogen-doped Ti3C2 (N–Ti3C2), resulting in the creation of innovative interface engineered N–Ti3C2/MnO2 nanosheets. Due to its distinctive heterostructure and favourable interfacial interaction, the N–Ti3C2/MnO2 electrode shows better performance in both the hydrogen and oxygen evolution reactions, exhibiting low overpotentials of 130 mV and 289 mV, respectively, at a current density of 10 mA cm−2. Furthermore, it requires a cell voltage of 1.7 V to achieve a current density of 10 mA cm−2 during the overall water splitting process. The N–Ti3C2/MnO2 composite also maintains sustained durability for a period of 4 h. This enhanced electrochemical activity of N–Ti3C2/MnO2 can be due to the synergistic effects resulting from the intricate contact between N–Ti3C2 and MnO2. This research presents a simple methodology for designing MXenes-based multicomponent electrodes for electrochemical water splitting reactions and its potential application for electrochemical water splitting.

La implanted band engineering of ZnO nanorods for enhanced photoelectrochemical water splitting performance

In the quest to improve photoelectrochemical water-splitting performance, we have doped lanthanum (La) in highly crystalline zinc oxide (ZnO) nanorods (NRs) using a facile and low-temperature hydrothermal route and successful substitution of La3+ at the Zn2+ site is confirmed from structural and chemical analysis. The tapered NRs morphology gained after La doping resulted in lower optical bandgap of 3.17 eV, enhanced visible light trapping, and multiphoton absorption, which assist in achieving good PEC activity. The La doping also offered higher Urbach energy (EU), subsidizing the number of oxygen vacancies. The UPS spectra show that La doping reduces conduction band energy level and endorses smooth charge transportation. The La-doped ZnO exhibits two times enhancement in photocurrent (1.54 mA·cm−2) compared to pristine ZnO (0.81 mA·cm−2). The higher applied bias to the photon conversion efficiency of ∼1.14% for La-doped ZnO confirms the efficient utilization of solar energy. The EIS measurements demonstrated reduction in charge transfer resistance with La-doping. Mott-Schottky analysis shows that La doping lowers the flat-band potential and enhances charge transportation, making it a potential photoanode for PEC water-splitting applications.

Dual Polarization Strategy for Boosting Electron-Hole Separation toward Overall Water Splitting within Ferroelectric β-AIBIIIO2 (BIII = P3+, As3+, Sb3+, and Bi3+ for Lone Pairs).

Ferroelectric materials, leveraging an inherent built-in electric field, are excellent in suppressing electron-hole recombination. However, the reliance solely on bulk polarization remains insufficient in enhancing carriers' separation and migration, limiting their practical application in photocatalytic overall water splitting (POWS). To address this, we incorporated cations with ns2 lone pairs (P3+, As3+, Sb3+, and Bi3+) into ferroelectric semiconductors, successfully constructing 44 β-AIBIIIO2 photocatalysts with dual polarization. Through rigorous first-principles calculations and screenings for stability, band characteristics, and polarization, we identified four promising candidates: β-LiSbO2, β-NaSbO2, β-LiBiO2, and β-TlBiO2. Within these materials, lone pairs induce local polarization in the xy-plane. Additionally, out of the plane, there is robust bulk polarization along the z-direction. This synergistic effect of the combined local and bulk polarization significantly improves the separation efficiency of electron-hole pairs. Explicitly, the electron mobility of the four candidates ranges from 105 to 106 cm2 s-1 V-1, while the hole mobility also increases significantly compared to single-phase polarized materials, up to 106 cm2 s-1 V-1. Notably, β-TlBiO2 is predicted to achieve a solar-to-hydrogen (STH) efficiency of 17.2%. This study not only offers insights for water-splitting catalyst screening but also pioneers a path for electron-hole separation through the dual polarization strategy.

Recent Progress of Ion-Modified TiO2 for Enhanced Photocatalytic Hydrogen Production.

Harnessing solar energy to produce hydrogen through semiconductor-mediated photocatalytic water splitting is a promising avenue to address the challenges of energy scarcity and environmental degradation. Ever since Fujishima and Honda's groundbreaking work in photocatalytic water splitting, titanium dioxide (TiO2) has garnered significant interest as a semiconductor photocatalyst, prized for its non-toxicity, affordability, superior photocatalytic activity, and robust chemical stability. Nonetheless, the efficacy of solar energy conversion is hampered by TiO2's wide bandgap and the swift recombination of photogenerated carriers. In pursuit of enhancing TiO2's photocatalytic prowess, a panoply of modification techniques has been explored over recent years. This work provides an extensive review of the strategies employed to augment TiO2's performance in photocatalytic hydrogen production, with a special emphasis on foreign dopant incorporation. Firstly, we delve into metal doping as a key tactic to boost TiO2's capacity for efficient hydrogen generation via water splitting. We elaborate on the premise that metal doping introduces discrete energy states within TiO2's bandgap, thereby elevating its visible light photocatalytic activity. Following that, we evaluate the role of metal nanoparticles in modifying TiO2, hailed as one of the most effective strategies. Metal nanoparticles, serving as both photosensitizers and co-catalysts, display a pronounced affinity for visible light absorption and enhance the segregation and conveyance of photogenerated charge carriers, leading to remarkable photocatalytic outcomes. Furthermore, we consolidate perspectives on the nonmetal doping of TiO2, which tailors the material to harness visible light more efficiently and bolsters the separation and transfer of photogenerated carriers. The incorporation of various anions is summarized for their potential to propel TiO2's photocatalytic capabilities. This review aspires to compile contemporary insights on ion-doped TiO2, propelling the efficacy of photocatalytic hydrogen evolution and anticipating forthcoming advancements. Our work aims to furnish an informative scaffold for crafting advanced TiO2-based photocatalysts tailored for water-splitting applications.

Solvated Electrons Generated on the Surface of Na-SPHI for Boosting Visible Light Photocatalytic Hydrogen Evolution with Ultra-High AQE.

Enhancing the utilization of visible-light-active semiconductors with an excellent apparent quantum efficiency (AQE) remains a significant and challenging goal in the realm of photocatalytic water splitting. In this study, a fully condensed sulfur-doped poly(heptazine imide) metalized with Na (Na-SPHI) is synthesized by an ionothermal method by using eutectic NaCl/LiCl mixture as the ionic solvent. Comprehensive characterizations of the obtained Na-SPHI reveal several advantageous features, including heightened light absorption, facilitated exciton dissociation, and expedited charge transfer. More importantly, solvated electron, powerful reducing agents, can be generated on the surface of Na-SPHI upon irradiation with visible light. Benefiting from above advantage, the Na-SPHI exhibits an excellent H2 evolution rate of 571.8 µmol·h-1 under visible light illumination and a super-high AQE of 61.7% at 420nm. This research emphasizes the significance of the solvated electron on the surface of photocatalyst in overcoming the challenges associated with visible light-driven photocatalysis, showcasing its potential application in photocatalytic water splitting.

Electrochemical and dielectric analysis of multifunctional GQDs@PEG@Mg-ZnFe2O4 ternary nanohybrid for low-frequency electronics, water splitting, and sustainable energy storage applications

This work explores the potential of GQDs@PEG@Mg-ZnFe2O4 nanocomposite in water splitting and energy storage applications. The synthesized hybrid showed remarkable dielectric properties indicating its potential for low-frequency telecommunications and electronics applications. The impedance spectroscopy disclosed the contribution of grains and grain boundaries in the realization of colossal permittivity (104) in GQDs@PEG@Mg-ZnFe2O4. Moreover, GQDs@PEG@Mg-ZnFe2O4 showed excellent energy storage performance, indicated by its specific capacitance of 100 Fg−1 and a retention ratio of 99 % over 1000 cycles at a 1 Ag−1 current density. GQDs@PEG@Mg-ZnFe2O4 nanohybrid also showed remarkable electrocatalytic activity, both for hydrogen evolution reaction and oxygen evolution reaction. The determined Tafel slope value was found to be 90 mVdec−1 and 110 mVdec−1 at a 10 mA/cm2 current density, respectively. These results highlight the multifunctional nature of the GQDs@PEG@Mg-ZnFe2O4 nanocomposite and its potential as a versatile material to address challenges in both energy storage and conversion technologies.

Structural insights, synthesis, and electrocatalysis of high entropy nanoparticles for fuel cell, metal-air battery, and water-splitting applications

High-entropy alloy nanoparticles (HEA-NPs) have recently sparked great interest in materials science. Their solid-solution states, derived from distinct HEA configurations, make them promising candidates for catalysts with exceptional activity, stability, and tunable performance. However, a comprehensive understanding of the underlying mechanisms governing their electrocatalytic behavior is still lacking, hindering the rational design of HEA electrocatalysts. This review summarizes the fundamental knowledge of HEA-NPs, including the structure-activity correlations of HEA-NPs, diverse synthesis strategies, and applications in electrochemical catalysis. The design strategies for guiding improvements in tunable performance were highlighted. The article concludes with insights, perspectives, and future directions, encapsulating the state-of-the-art knowledge and paving the way for further exploration in this dynamic field.

Space confined growth of RuO2/Ru carbon nanorods for highly efficient electrocatalytic hydrogen evolution

Exploring efficient and robust electrocatalysts with low cost for hydrogen evolution reaction (HER) is critical for practical application of electrochemical water splitting. Ru-based platinum group electrocatalysts shows great potential in HER, however, Ru suffer from sluggish kinetics of water dissociation for electrochemical reduction of water to hydrogen in alkaline environments. Here, oxygen atoms are introduced into Ru by simple secondary heat treatment to form Ru–O–C bonds to weak the strength of Ru–H bond. The overpotential of the catalyst is only 19 mV at 10 mA cm−2 and the stability is greatly improved. Theoretical calculations reveal that the Ru–O–C structure formed in RuO2 facilitates the dissociation of H–OH, which is the rate-determining step in alkaline electrolytes, leading to significant improvement in HER activity.

In-situ fabrication of self-supported cobalt molybdenum sulphide on carbon paper for bifunctional water electrocatalysis

The fabrication of highly efficient yet stable noble-metal-free bifunctional electrocatalysts that can simultaneously catalyse both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains challenging. Herein, we employ the heterostructure coupling strategy, showcasing an aerosol-assisted chemical vapour deposition (AACVD) aided synthetic approach for the in-situ growth of cobalt molybdenum sulphide nanocomposites on carbon paper (CoMoS@CP) as a bifunctional electrocatalyst. The AACVD allows the rational incorporation of Co in the Mo–S binary structure, which modulates the morphology of CoMoS@CP, resulting in enhanced HER activity (ŋ10 = 171 mV in acidic and ŋ10 = 177 mV in alkaline conditions). Furthermore, the CoS2 species in the CoMoS@CP ternary structure extends the OER capability, yielding an ŋ100 of 455 mV in 1 M KOH. Lastly, we found that the synergistic effect of the Co–Mo–S interface elevates the bifunctional performance beyond binary counterparts, achieving a low cell voltage (1.70 V at 10 mA cm−2) in overall water splitting test and outstanding catalytic stability (∼90 % performance retention after 50-/30-h continuous operation at 10 and 100 mA cm−2, respectively). This work has opened up a new methodology for the controllable synthesis of self-supported transition metal-based electrocatalysts for applications in overall water splitting.

Robust in-plane ferroelectricity, high hole mobility, and low thermal conductivity in GeO monolayer: A first-principles study

Motivated by the experimental advancements in 2D crystalline germanium oxides, we investigated the electronic and transport properties of GeO and GeO2 monolayers (MLs) using first-principles calculations. GeO ML exhibits an in-plane ferroelectricity until the melting point of 1100 K. Compressive strain facilitates polarization reversion by lowering the ferroelectric transition barrier. The band edges meet the requirements for photocatalytic water splitting across a wide variety of strains. Meanwhile, GeO ML has a high hole mobility of 4854 cm2/V⋅s along the y-axis, owing to its low deformation potential constant. The large difference in hole and electron mobility promotes electron–hole separation. In addition, GeO ML has a low thermal conductivity of κx = 3.37 W/mK and κy = 12.53 W/mK at 300 K, due to the strong anharmonicity caused by lone-pair electrons. In contrast, GeO2 ML has an isotropic electron mobility of 382 cm2/V⋅s and an κ of 22.60 W/mK at 300 K. At last, we discussed the probable reaction to grow 2D GeO crystal and calculated the Raman intensity to distinguish it in future experiments. Our results show that 2D GeO has potential applications in ferroelectrics, thermoelectrics, and water splitting.

Heterostructured NiO/IrO2 synergistic pair as durable trifunctional electrocatalysts towards water splitting and rechargeable zinc-air batteries: An experimental and theoretical study

Constructing an ultra-durable trifunctional electrocatalyst with high efficiency for HER, OER and ORR has become critical for demanding water splitting and zinc air battery applications. Herein, we demonstrated a rational and efficient strategy to develop a porous nano foam like heterostructured NiO/IrO2 nano foam like electrocatalyst via a facile solvothermal and calcination approach. Experiments revealed that NiO/IrO2-NF shows outstanding HER (ƞ10=42mV), OER (ƞ10=240mV), and ORR (E1/2=0.80V) performances with lower overpotentials than many reported trifunctional electrocatalysts. Theoretical investigations on reaction mechanism of NiO/IrO2-NF, S-IrO2 and S-NiO were carried out using density functional theory calculations. The fabricated water electrolyzer required minimum cell voltage of 1.51V to reach 10mAcm-2 current density with outstanding durability of 600h and insignificant potential loss. Rechargeable zinc air battery with NiO/IrO2-NF air cathode displays a power density of 134.8mWcm-2 with excellent durability of 100/80/40h at 2/5/10mAcm-2.

Ti3C2 mediates the NiFe-LDH layered electrocatalyst to enhance the OER performance for water splitting

Oxygen evolution reaction (OER) is a very complex process with slow reaction kinetics and high overpotential, which is the main limitation for the commercial application of water splitting. Thus, it is of necessary to design high-performance OER catalysts. NiFe based layered double hydroxides (NiFe-LDHs) have recently gained a lot of attention due to their high reaction activity and simple manufacturing process. In this study, a novel electrocatalyst based on NiFe-LDH was constructed by introducing Ti3C2, which was utilized to modulate the structural and electronic properties of the electrocatalysts. Structural examinations reveal that the Ti3C2 of 2D structure successfully dope the NiFe-LDHs nanosheets, forming NiFe-LDH/Ti3C2 heterojunctions. Firstly, the heterojunction substantially reduces the charge transfer resistance, promoting the electron migration between the LDH nanosheets. Secondly, theoretical calculations demonstrate that the energy barrier between the rate-determining step from *OH to *O is lowered, favoring the formation of the reaction intermediates and thus the occurrence of OER. As a result, the composite electrocatalyst exhibits a low overpotential of 334 mV at a current density of 10 mA/cm2 and a small Tafel slope of 55 mV/dec, which are superior to those of the NiFe-LDH by 11.2 % and 38.5 %, respectively. This study provides inspiration for promoting the performances of NiFe based electrocatalysts by utilizing 2D materials.

Vertically Staggered Porous Ni2P/Fe2P Nanosheets with Trace Ru Doping as Bifunctional Electrocatalyst for Alkaline Seawater Splitting

AbstractDesigning a bifunctional electrocatalyst with high performance and low‐cost is of great significance to promote the large‐scale application of water splitting. Herein, porous Ru‐Ni2P/Fe2P heterojunction nanosheets with a vertically staggered structure are rationally fabricated to boost alkaline seawater splitting under large current densities. The Ru‐Ni2P/Fe2P catalyst exhibits remarkable activity in alkaline media, requiring only 274 and 331 mV at a large current density of 1000 mA cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Additionally, the NiFeOOH layer formed on the surface of Ru‐Ni2P/Fe2P is proposed as the active phase to promote the OER performance. Furthermore, an anion exchange membrane (AEM) electrolyzer assembled by Ru‐Ni2P/Fe2P electrocatalyst exhibits excellent long‐term durability over 100 h, achieving a current density of 500 mA−2 at 2.0 V in alkaline seawater at 60 °C. Theoretical calculations reveal that the Ni2P/Fe2P heterojunction integration with trace Ru leads to balanced adsorption and desorption properties. Moreover, the active sites of Ru‐Ni2P/Fe2P are confirmed, in which Ni site is favorable for HER and Fe site is conducive to OER. This work provides an insight into designing a highly efficient and cost‐effective bifunctional electrocatalyst for overall seawater splitting.

Advancements in Bipolar Membrane Electrodialysis Techniques for Carbon Capture.

Bipolar membrane electrodialysis (BMED) is a promising technology for the capture of carbon dioxide (CO2) from seawater, offering a sustainable solution to combat climate change. BMED efficiently extracts CO2 while generating valuable byproducts like hydrogen and minerals, contributing to the carbon cycle. The technology relies on ion-exchange membranes and electric fields for efficient ion separation and concentration. Recent advancements focus on enhancing water dissociation in bipolar membranes (BPMs) to improve efficiency and durability. BMED has applications in desalination, electrodialysis, water splitting, acid/base production, and CO2 capture and utilization. Despite the high efficiency, scalability, and environmental friendliness, challenges such as energy consumption and membrane costs exist. Recent innovations include novel BPM designs, catalyst integration, and exploring direct air/ocean capture. Research and development efforts are crucial to unlocking BMED's full potential in reducing carbon emissions and addressing environmental issues. This review provides a comprehensive overview of recent advancements in BMED, emphasizing its role in carbon capture and sustainable environmental solutions.

Exploring the effect of concentration on hydrothermally synthesized mesoporous spherical nanoflowers of bismuth tungstate for hybrid supercapacitor and water-splitting applications

This paper describes how the synergistic effect of concentration changes the electrode conductivity and enhances the electrochemical and electrocatalytic activities of bismuth tungstate nanoflowers (BWO NFs). This research mainly aims to develop mesoporous spherical BWO NFs using a hydrothermal route. The structural analysis of the BWO NFs revealed the presence of an orthorhombic phase with a regular atomic arrangement. Scanning electron microscopy revealed that the different BWO NFs samples had nonuniform spherical NFs, which play an important role in supercapacitor and electrocatalytic applications. The identification of functional groups and stretching–bending vibrations of Bi–W–O bonds are revealed by FT-IR and Raman spectroscopy respectively. Additionally, the transmission electron microscopy and X-ray photoelectron spectroscopy confirmed the morphological, structural, and electronic states of the BWO NFs. Furthermore, the supercapacitive and electrocatalytic activity of BWO–nickel foam (NF) electrodes were investigated using an aqueous 1 M KOH electrolyte. The results revealed that the BWO-2 electrode exhibited an improved specific capacity (Csp) of (647 F/g) 72 mAh/g and excellent capacitive retention of 81 % over 5000 cycles. An asymmetrical hybrid device was fabricated using a two-electrode cell with BWO–NF and reduced graphene oxide acting as the positive and negative electrodes, respectively. The device demonstrated favorable electrochemical properties: a Csp of 52 mAh/g at 5 mV/s as well as a Csp of 46 mAh/g, the highest energy density of 32 Wh/kg, and the highest power density of 2330 W/kg at 5 mA/cm2. Furthermore, the BWO NFs were investigated for water-splitting activity, and the BWO-2 electrode was found to exhibit better electrocatalytic performance (overpotential: 328 mV, Tafel slope: 80.9 mV/dec, and electrochemical surface area: 41.2 cm2) and stability than the other electrodes. The designed asymmetric structure offers a suitable cathode material for energy storage and electrocatalytic applications.

Immobilization of Prussian Blue Nanoparticles Onto Au‐Modified ZnIn2S4 Photoanode for Efficient Photoelectrochemical Water Splitting

AbstractZnIn2S4 has been regarded as a promising photoanode material for photoelectrochemical (PEC) water splitting. However, its severe charge recombination and low carrier transport efficiency limit practical applications in PEC water splitting. A novel ZnIn2S4/Au/PB photoanode was prepared by using the in‐situ photodeposition of Au nanoparticles and electrodeposition of Prussian blue (PB) nanoparticles onto ZnIn2S4 nanosheets. The photocurrent density of the prepared ternary photoanode reached 0.42 mA/cm2 at 1.23 VRHE, which is 6 times higher than pure ZnIn2S4. The introduction of Au nanoparticles remarkably improved the efficiency of carrier transport and separation. Additionally, the application of PB onto ZnIn2S4 resulted in an extended spectrum of light absorption. The incident photon‐to‐current efficiency (IPCE) value recorded was 24.6 % at 350 nm. This improvement can be attributed to the formation of a Z‐type heterojunction.

Solution-processed Sb2O3: A promising electrode material for high-performance supercapacitors and electrocatalysts

Easy accessibility, wide range of redox states, affordable cost, and simple synthesis methods of metal oxides have gained a significant interest in the domains of electrochemical supercapacitors and electrocatalysts. The successive ionic layer adsorption and reaction (SILAR) chemical synthesis approach has been introduced to preparing nanocrystalline antimony oxide (Sb2O3) for both energy storage and water splitting applications. The Sb2O3 electrode demonstrates a remarkable specific capacitance of 3011 F/g at a current density of 2 A/g in a 1 M solution of potassium hydroxide (KOH). The current design of the Sb2O3//Bi2O3 (bismuth oxide) asymmetric electrochemical supercapacitor device has endowed a specific capacitance of 391 F/g, a maximum energy density of 78.2 Wh/Kg at a power density of 1000 W/Kg, and an outstanding capacitance retention of 77 % even after 5000 redox cycles. The Sb2O3 electrode demonstrates outstanding performance in the oxygen evolution process at a current density of 10 mA cm2, with an overpotential of 206 mV. The Sb2O3 as an electrocatalyst also exhibits exceptional results in the hydrogen evolution reaction with an overpotential of 124 mV/dec. Both of these electrochemical processes are distinguished by the evolution of oxygen which is capable of facilitating the process of water splitting to obtain clean energy for day by day growing population.

FeNi alloys incorporated N-doped carbon nanotubes as efficient bifunctional electrocatalyst with phase-dependent activity for oxygen and hydrogen evolution reactions

Electrochemical oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are two important half-cell reactions for overall water splitting. The rational design and fabrication of efficient electrocatalysts involving nonprecious-metals and carbon matrix is highly attractive. Herein, a series of N-doped carbon nanotubes encapsulated FeNi alloy nanoparticles (FeNi@NCNTs) are synthesized via a simple pyrolysis treatment of Fe-doped Ni(OH)2 precursors under the assistance of dicyandiamine source. The results reveal that the Fe/Ni ratio has an obvious influence on the morphology and phase composition of FeNi@NCNTs series, thus affecting the electrocatalytic performance. The highest electrocatalytic activity is achieved for the Fe1Ni4@NCNTs product with a Fe/Ni molar ratio of 1:4, which delivers low overpotentials of 278 and 279 mV for OER and HER at 10 mA cm−2 in 1.0 mol/L KOH, respectively. The intriguing electrocatalytic performance is mainly ascribed to the advantageous integration of rambutan-like hierarchically porous structure and composition optimization, significantly facilitating the fast mass/charge transfer as well as promoting the adsorption ability for intermediates. The present method may open a facile avenue for developing cost-effective, high-activity, and stable electrocatalysts for the application of overall water splitting.

Multiphase Fe-doped Ni3S2/MoOx electrocatalyst prepared by facile one-step hydrothermal for full-cell water splitting: Effect of Mo on physical and electrochemical properties

Herein, we develop a multiphase strategy to improve the HER performance by incorporating the MoOx phase with the addition of MoCl5 during the one-step hydrothermal. Adding MoCl5 at 0.5 mmol (MFN-0.5) yields the best HER performance, with an overpotential of 261 mV at a current density of 100 mA/cm2. The MFN-0.5 catalyst exhibits excellent performance for both HER and OER, enabling it to drive full-cell water splitting with cell potentials of 1.50 and 1.71 V at 10 and 100 mA/cm2, respectively. We further scale up the MFN-0.5 (4 ×4 cm2) for a single stack-cell electrolyzer, requiring a cell potential of 1.85 V to achieve a large current density of 250 mA/cm2. Incorporating the MoOx phase accelerates the water dissociation step and protects the metal sulfide surface from oxidation under anodization in an alkaline environment. Our findings offer a promising approach for developing highly efficient catalysts for electrolytic water-splitting applications.

Construction of Heterostructured NiS/NiSe2 and their application in electrocatalytic water splitting

Development of non-precious metal electrocatalyst that can efficiently catalyze the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) simultaneously, is a great challenge. Herein, density functional theory (DFT) calculations are first conducted to explore the beneficial effect of NiSe2/NiS heterostructure on OER. Based on this, a series of nickel selenosulfides constructed by different amounts of NiS and NiSe2 are synthesized. Results indicate that Ni4–Se2–S2 with the NiS to NiSe2 ratio of 5.82/2.47 displays outstanding electrocatalytic activity for OER/HER, with overpotentials of 228 mV and 155 mV at 10 mA cm−2, respectively. Moreover, a two-electrode electrolyzer using Ni4–Se2–S2 as the anode and cathode exhibits a lower voltage than RuO2||Pt/C. Moderate ratio of NiS to NiSe2 achieves a balance between conductivity and surface area, which endows Ni4–Se2–S2 the best catalytic performances. Our results pave a way for the optimization of heterostructured catalysts.