Electrode For Hydrogen Evolution Research Articles

Highly Durable Nanoporous Cu2-xS Films for Efficient Hydrogen Evolution Electrocatalysis under Mild pH Conditions.

Copper-based hydrogen evolution electrocatalysts are promising materials to scale-up hydrogen production due to their reported high current densities; however, electrode durability remains a challenge. Here, we report a facile, cost-effective, and scalable synthetic route to produce Cu2-xS electrocatalysts, exhibiting hydrogen evolution rates that increase for ∼1 month of operation. Our Cu2-xS electrodes reach a state-of-the-art performance of ∼400 mA cm-2 at -1 V vs RHE under mild conditions (pH 8.6), with almost 100% Faradaic efficiency for hydrogen evolution. The rise in current density was found to scale with the electrode electrochemically active surface area. The increased performance of our Cu2-xS electrodes correlates with a decrease in the Tafel slope, while analyses by X-ray photoemission spectroscopy, operando X-ray diffraction, and in situ spectroelectrochemistry cooperatively revealed the Cu-centered nature of the catalytically active species. These results allowed us to increase fundamental understanding of heterogeneous electrocatalyst transformation and consequent structure-activity relationship. This facile synthesis of highly durable and efficient Cu2-xS electrocatalysts enables the development of competitive electrodes for hydrogen evolution under mild pH conditions.

Self-assembled CoS/S-rGO dual-functional composite, and reliable hydrogen evolution performance in both acidic and alkaline media

Developing an amphoteric-functional hydrogen evolution electrode that is useable in both acidic and alkaline electrolytes is an innovative future energy strategy. Here, CoS/S-rGO/CP electrode is obtained by direct hydrothermal growth of CoS loaded on S-rGO onto carbon paper (CP). The introduction of S reduces defects in the hexagonal carbon rings in rGO. CoS/S-rGO/CP electrode is slightly more stable in acidic one (0.5 M H2SO4) than in alkaline (1.0 M KOH) electrolytes. This is because S ion elution from CoS or S-rGO is suppressed due to the presence of SO42− ion, a common ion, in the acid electrolyte. Gibbs free energy calculations suggest that the overall rate in the alkaline electrolyte is thermodynamically slightly slower than in the acidic electrolyte due to the lower H∗ coverage. In CoS/S-rGO/CP, S in S-rGO donates electrons to Co2+ in CoS, while S in CoS repels electrons to C=S in S-rGO, resulting in there is a strong synergy between CoS and S-rGO. Eventually, CoS/S-rGO/CP electrode exhibits faradaic efficiencies of 97.85% and 97.01% in acidic and alkaline electrolytes with overpotentials of −0.20 and −0.22 V, and Tafel slopes of 89.2 and 96.1 mV dec−1, respectively. In particular, the electrode performs almost as well as commercial Pt/CP under the same reaction conditions, highlighting its future commercialization prospects as a noble-metal-free HER electrode.

Alkaline hydrogen production promoted by small-molecule modification on flowerlike Co2(OH)2CO3

Developing a low-cost and high-efficiency nonprecious metal-based catalyst for hydrogen evolution reaction (HER) is of great significance for the utilization of hydrogen energy. In this work, we report a molecular-modification strategy to fabricate a self-supported hydrogen evolution electrode, specially by grafting the macrocyclic molecules (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) on the surface of a cobaltous dihydroxycarbonate (COC) seed layer. The HHTP-COC electrode is endowed with a rod-like structure, which provides favorable access for charge transportation and mass exchange. The macrocyclic molecule structure in HHTP can be grafted on COC and improve the electrical conductivity, while the interaction between HHTP and COC induces the rearrangement of charge configuration on the surface. Due to the combination effects of several aspects, the HHTP-COC electrode achieves astonishing HER activity, with a low overpotential of 61.0 mV (η10, at the current density of 10 mA cm−2) and excellent stability in alkaline condition. This kind of interface engineering based on the organic molecules can be applied to the design and manufacture of electrocatalysts in the field of energy conversion and storage.

Wood‐Derived, Monolithic Chainmail Electrocatalyst for Biomass‐Assisted Hydrogen Production

AbstractThe chainmail catalyst by encapsulating an active species within the carbon support is a well‐established concept to endorse extraordinary stability for catalytic reactions under harsh conditions. Conventional chainmail catalysts inevitably suffer from poor accessibility to active sites, leading to extra voltage to compensate the sluggish diffusion kinetics in electrocatalysis. Herein, the naturally abundant wood material is converted into a monolithic chainmail electrocatalyst by encapsulating cobalt nanoparticles within N‐doped carbonized wood. Such a monolithic chainmail catalyst is employed directly as electrode for hydrogen evolution (HER), oxygen evolution (OER), and monosaccharide oxidation reactions (MOR) with benchmark performance. By coupling the HER with MOR, the electrolyzer equipped with the monolithic chainmail catalyst allows hydrogen production at a current density of 100 mA cm−2 with a full cell voltage of only 1.36 V. Such design of wood‐derived chainmail catalyst provides a promising way to fabricate robust electrocatalysts for future production of hydrogen and value‐added chemicals.

Electroless deposition of Ni-W-P films as binder-free, efficient and durable electrode for electrochemical hydrogen evolution

The electrocatalytic characteristics of Ni-W-P electroless coatings were investigated in this work. Coatings with varying amounts of W and P were deposited, with the elemental analysis results revealing that the alkaline baths had superior alloying element adsorption in the coating. Linear Sweep Voltametry (LSV) test showed that the sample coated in the alkaline bath with 16 g/l Na2WO4 featured the best electrocatalytic behavior with a phosphorus and tungstate content of around 5.7% and 5.8%, respectively, and η10 = -181 mV. Furthermore, the X-Ray Diffraction (XRD) experiment revealed the crystal structure alterations owing to the presence of tungsten elements, which was an influential factor in enhancing the resultant electrocatalytic characteristics. Finally, the coating electrocatalytic stability was assessed using chronoamperometry, CV, and stepwise chronoamperometry tests, demonstrating the WH16 sample, to be a viable candidate for producing a durable electrode generation with good stability.

Electroless deposition of Ni-W-Mo-Co-P films as a binder-free, efficient and durable electrode for electrochemical hydrogen evolution

In this study, the manufacture of Ni-W-Mo-Co-P, Ni-Mo-Co-P, Ni-W-Co-P, Ni-W-Mo -P, Ni-Co-P, Ni-Mo-P, Ni-W-P, and Ni-P alloying coatings through electroless method on the copper substrate was investigated. The elemental and structural tests showed that the alteration of the Ni-P electroless basic bath composition by introducing sodium tungstate, sodium molybdate, and cobalt chloride additives enabled the deposition of alloying coatings. Linear Sweep Voltametry (LSV) tests revealed that the Ni-W-Mo-Co-P sample (NWMCP) coated in an alkaline bath with 18 g/l Nickel (II) sulfate, 12 g/l Ammonium acetate, 12 g/l Sodium citrate, 12 ml Lactic acid, 12 g/l Sodium hypophosphite, 8 g/l Sodium tungstate, 0.2 g/l Sodium molybdate, and 10 g/l Cobalt (II) chloride was featured with the best electrocatalytic properties with η10 = −41, η20 = −46, η100 = −67 mV and tafel slope of 38 mV.dec−1. Scanning Electron Microscope (SEM) observations and Cyclic Voltametry (CV) electrochemical tests showed that morphology had a negligible effect on electrocatalytic performance of the coating. In addition, the presence of alloying elements improved the coating intrinsic properties by changing its electronic structure. Electrocatalytic stability was assessed using chronoamperometry, cyclic voltammetry, and stepwise chronoamperometry tests, introducing NWMCP sample a durable electrode generation with good stability.

The dynamics of the nickel foam formation and its effect on the catalytic properties toward hydrogen evolution reaction

Porous nickel deposits were obtained by electrodeposition via dynamic hydrogen bubble template in a galvanostatic mode at a current density of 0.3, 0.6, 0.9 and 1.2 A·cm−2. Change of nickel foam morphology (dendrite particles, pore number and their sizes) with the applied current density was analyzed. It was found that at low hydrogen evolution rate, a gradual formation of a porous structure occurs, while at high ones, the formation of the template structure ends in the first minutes of electrolysis. It is shown that the log-normal distribution can be used to describe the formation of a hydrogen template as a system of nickel foam macropores. The catalytic activity of nickel foams toward hydrogen evolution was analyzed in an alkali solution. The Tafel slope for the obtained foams is in the range of 126-107 mV·dec−1. Nickel foams obtained at 1.2 A·cm−2 are the best candidates for hydrogen evolution electrodes due to their stable structure, providing maximum access of reacting particles to the inner surface of the electrode.

Adjacent atomic cobalt sites anchored on carbon foam as a self-supporting electrode for efficient hydrogen evolution

Based on the MOF derivation strategy of inkjet printing, carbon foam supported Co–N single atom catalysts was synthesized, which formed adjacent but dispersed Co single atom sites to promote hydrogen evolution.

Synthesis of self-supported metal fiber felt electrode for electrocatalytic hydrogen evolution

• Using stainless steel fiber felt as the substrate. • Pt is electrodeposited on the substrate. • Pt-316L-0.1 exhibite the excellent HER performance. Self-supported metal fiber felt electrode was synthesized by the electrodeposition method, and the catalytic activities in the hydrogen evolution reaction (HER) were investigated. The results showed that when the stainless steel fiber felt 316L was used as the base material and the Pt loading was about 0.5 mg·cm -2 , the obtained sample Pt-316L-0.1 exhibited the best electrocatalysis hydrogen evolution performance and stability. In 0.5 M H 2 SO 4 , its hydrogen evolution overpotential is 44 mV, and the Tafel slope is 55 mV·dec -1 . It is worth mentioning that Pt-316L-0.1 also has the highest electrochemical double-layer capacitance value (114.06 mF·cm -2 ), indicating that it has a large electrochemical active area and abundant active sites. It indicates that the self-supported electrode is favorable for hydrogen precipitation reaction, which provides a new direction for the design of electrode materials for industrial water electrolysis for hydrogen evolution.

Macroporous NiMo alloy self-supporting electrodes for efficient hydrogen evolution at ultrahigh current densities

In this paper, a porous array NiMo alloy electrode is designed. The multi-scale pore structure and super-wetted surface of the electrode make mass transfer rapid, which ensures that the precipitated H2 bubbles are removed in time.

Screening Nickel-Doped Mo2 C Nanorod Arrays for Ultrastable and Efficient Hydrogen Evolution over a Wide pH Range.

Green hydrogen, using sustainable energy to decompose water to produce hydrogen, is regarded as the ideal and effective connection to convert electricity into chemical energy. Herein, well designed Ni-doped Mo2 C nanorod electrodes self-supported on three types of substrates (Ni foam, Cu foam and stainless steel wire mesh) with outstanding gas resistance and prominent corrosion resistance were assembled together to build up a wide pH applicable electrode for Hydrogen Evolution. In particular, Ni-doped Mo2 C nanorod arrays on stainless steel wire mesh donated as Ni-Mo2 C@SSW exhibited remarkable electrocatalytic properties towards hydrogen evolution reaction with superior overpotentials both in 1 M KOH and 0.5 M H2 SO4 (102 mV and 106 mV at the current density of 10 mA cm-2 ) and incomparable continuous durability. This work provides the possibility for the realization of low cost, high activity and ultra-stable durability HER electrocatalysts in practical industrial application.

Constructing a NiMnS electrode with a Mn-rich surface for hydrogen production in anion exchange membrane water electrolyzers.

Efficient alkaline hydrogen evolution electrodes must be used for hydrogen production in anion exchange membrane water electrolyzers (AEMWEs). Therefore, we fabricated a NiMnS catalyst with a Mn-rich surface, which was self-supported on Ti paper through one-step electrodeposition. Mn doping endowed the catalyst with a unique hollow morphology and lattice-distorted structure. Consequently, the NiMnS/Ti electrode exhibited a large number of exposed electrochemical surfaces and effective active sites and a high hydrogen evolution reaction (HER) activity. Specifically, in half-cell measurements, the NiMnS/Ti electrode exhibited an overpotential of 65 mV at 10 mA cm-2, which was lower than that of NiS/Ti (102 mV) and indicated its superior HER activity. When the proposed cathode was applied in an AEMWE single cell, the device achieved a high current density of up to 0.9 A cm-2 at a cell potential of 2.0 V.

Self-Adhesive Ionomers for Alkaline Electrolysis: Optimized Hydrogen Evolution Electrode

Hydrogen produced through low-temperature water electrolysis using anion exchange membranes (AEM) combines the benefits of liquid-electrolyte alkaline electrolysis and solid-polymer proton exchange membrane electrolysis. The anion conductive ionomers in the oxygen-producing anode and hydrogen-producing cathode are a critical part of the three-dimensional electrodes. The ionomer in the hydrogen-producing cathode facilitates hydroxide ion conduction from the cathode catalyst to the anode catalyst, and water transport from the anode to the cathode catalyst through the AEM. This ionomer also binds the catalyst particles to the porous transport layer. In this study, the cathode durability was improved by use of a self-adhesive cathode ionomer to chemically bond the cathode catalyst particles to the porous transport layer. It was found that the cathode ionomers with high ion exchange capacity (IEC) were more effective than low IEC ionomers because of the need to transport water to the cathode catalyst and transport hydroxide away from the cathode. The cathode durability was improved by using ionomers which were soluble in the spray-coated cathode ink. Optimization of the catalyst and ionomer content within the cathode led to electrolysis cells which were both mechanically durable and operated at low voltage.

Development of self-supporting catalyst based on bionic honeycomb communication channel from biomass cork waste for hydrogen evolution

It is a great challenge to achieve an efficient hydrogen evolution reaction (HER) in the alkaline medium. Multi-layer functional carbon can provide abundant anchor points for metal nanostructures, showing great potential in improving the catalytic activity of electrolyzed water in the alkaline medium. Inspired by honeybee hives, an efficient hydrogen evolution electrode (RuNi-LMH@NCNT/CW) is developed by structuring multi-directional N-doped carbon nanotubes on porous carbonized cork (CW), which encapsulates Ru/RuNi nanoparticles uniformly grown on NiO/Ni(OH)2 nanostructures. Interestingly, the whole encapsulation of NiO/Ni(OH)2 nanostructured doped Ru/RuNi nanoparticles by carbon nanotubes are obtained. The exposed active edges of multilayer porous nanostructures and the high conductivity of the carbonized cork jointly improve the electrocatalytic performance of HER. Specifically, the RuNi-LMH@NCNT/CW electrode shows an over potential as low as 67 mV, achieves excellent HER activity with a current density of 10 mA cm−2 in 1 M KOH solution, and illustrates a low Tafel slope of 41.3 mV dec−1, having excellent stability in alkaline medium. This study provides a bionic composite structure for electrolyzing water to produce hydrogen. In addition, to a certain extent, this study solves the problem that it is difficult to load active particles caused by the cork sealing cell structure.

On the Suitability of Proton Pump Experiments to Evaluate New Hydrogen Evolution Electrodes for PEM Electrolysis Cells

The increased interest in green hydrogen has fostered an increased interest in electrolysis technology and in particular PEM-electrolysis as it allows currently best to absorb intermittent occurring renewable excess current. The challenge is the high expenditure of scarce PGM materials in PEM electrolysis cells. While this is most relevant for the iridium used as anodic oxygen evolution catalyst still also a reduction of the platinum expenditure at the cathode would at least serve to the Capex for PEMEL facilities. The group of Prof. U. Apfel at Ruhr University Bochum and Fraunhofer UMSICHT in Oberhausen is investigating pentlandite based hydrogen evolution catalyst for this purpose1 . Within the Fraunhofer internal project CINES, Fraunhofer ICT had the task to develop hydrogen evolution electrode from this catalyst. Now, as the hydrogen evolution and hydrogen oxidation in an acidic environment are both very fast reactions2 the difficulty is to monitor this reaction in a full electrolysis cell versus a oxygen evolution electrode with much more sluggish reaction. The idea was therefore to employ proton pumping as experiment wherein the electrode which is tested is used as cathode and a standard Pt/C electrode at a reasonable platinum loading as anode. In that way the performance of the new hydrogen evolution electrode should be much easier to evaluate.In a first step a commercial fuel cell CCM bought at Quintech, Germany was compared to a homemade CCM with platin layers on both sides both operated as proton pump. The results show that the performance differ in detail. So, the initial voltage loss due to charge transfer resistance is smaller for the commercial CCM likely due to the use of a more performant catalyst. The homemade CCM perform better however in the ohmic region. For both type of CCM the voltage at 800 mA cm-2 did not exceed -0.12 V (cf. Fig 1).In comparison first test with the Pentlandite based HER catalyst showed a strong over potential increase at low current densities and a hysteresis between the forward and the backward scan. The strength of the hysteresis did depend on the type of pentlandite (cf. Fig 2). After discussion with Prof Apfel’s group the effect of hot pressing was evaluated. It was found that hot pressing helped to reduce the over potential and in particular strongly reduce the hysteresis of the polarization curves (cf. Fig 3).If the results from the proton pumping are now compared to results obtained in a PEM electrolyser cell (cf. Fig. 4) it becomes obvious that many features observed in the proton pump experiments can be found here to. This is in particular true for the strong potential increase at low current densities.In total it can be said that proton pump experiments can be used to evaluate hydrogen evolution catalyst for PEM electrolysis at least in an initial stage. More experiments and details will be discussed in the presentation. B. Konkena, K. junge Puring, I. Sinev, S. Piontek, O. Khavryuchenko, J. P. Dürholt, R. Schmid, H. Tüysüz, M. Muhler, W. Schuhmann and U.-P. Apfel, Nat Commun, 7(1), 12269 (2016).J. Durst, C. Simon, A. Siebel, P. J. Rheinländer, T. Schuler, M. Hanzlik, J. Herranz, F. Hasché and H. A. Gasteiger, ECS Transactions, 64(3), 1069–1080 (2014). Figure 1

(Invited) Low Temperature PEM Cells Leveraging Hydrogen and Oxygen Evolution Electrodes

Proton exchange membrane-based electrochemical devices have been growing in commercial relevance, from fuel cells for automotive and other vehicle applications to hydrogen production and energy storage applications. These membranes are highly versatile, able to operate with both vapor and liquid feed systems, different cation conductors, and with different redox chemistries such as for flow batteries. This talk will focus on electrolyzer advancements in PEM systems and related synergies with flow batteries and CO2 electrolysis, which each share an electrode with water electrolyzers.Renewable hydrogen generation is a key enabler for decarbonization. The need for a sustainable source of hydrogen has been widely recognized: carbon dioxide re-utilization requires hydrogen to make useful chemicals, and ammonia production is one of the largest industrial demands for hydrogen. Over 95% of hydrogen is currently made from fossil fuels, generating CO2 as a byproduct; this reality needs to change in order to reach sustainability. Currently, the only commercial options for hydrogen production from water are alkaline electrolysis and PEM electrolysis, which will need to be leveraged to make impact in the near term before less mature technologies like solid oxide electrolysis become viable at scale. PEM technology has considerable opportunity for cost reduction and performance improvement, based on many years of research and development in the related PEM fuel cells.To accelerate this progress in a still emerging market, enlarging the field by working in similar technology areas is helpful. Flow battery research based on hydrogen cells, such as hydrogen halide and hydrogen iron batteries, can validate low catalyst loadings for the hydrogen evolution electrode, and advance coatings for hydrogen embrittlement resistance. Similarly, carbon dioxide electrolysis involves reduction of carbon dioxide on one electrode, but splitting water to evolve oxygen at the other. As another area of research gaining significant interest, CO2 electrolysis can help enable advanced porous transport layer development and oxygen evolution catalyst advancements, and eventually help drive component volumes. In this talk, opportunities and progress benefitting these technologies will be discussed.

Role of Ionomer Dispersion in the Design of Microstructure of Catalyst Layers: Oxygen and Hydrogen Evolution Reactions

Green hydrogen production is importance in the upcoming hydrogen economy era. Proton exchange membrane (PEM) water electrolysis is one of the most important technology to produce the green hydrogen that requires only water and extra electricity supplied from renewable energy. Main component, i.e., membrane electrode assembly (MEA), is a key part consisting of polymer electrolyte membrane and two electrodes which are oxygen evolution reaction (OER) electrode and hydrogen evolution (HER) electrode. Both electrode should be coated on the surface of membranes for better performance and mass production. Catalyst layers for OER and HER electrodes are composed of an electrocatalyst (Pt/C) and proton conducting ionomer. In the previous literature, proton conducting ionomer directly affects their performance and durability. Thus, the optimized design of the microstructure of the catalyst layers is essential. In this study, for the reduction of hydrogen production cost, highly dispersed ionomers were introduced to develop the optimized catalyst layers for OER and HER. The effect of dispersing solvents for ionomers on the performance and durability of catalyst layers was mainly investigated. Developed ionomer dispersions showed higher performance and durability in PEM water electrolysis, which result was made by the electrochemical characterization such as I-V polarization, voltage increasing rate during durability test, and so on as well as the microscopic characterization such as SEM and TEM were carried out to evaluate the effect of ionomer dispersions on the performance and durability of HER electrode in PEM water electrolysis. Acknowledgments This research was supported in part by the Hydrogen Energy Innovation Technology Development Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT ＆ Future Planning (NRF-2019M3E6A1063677) and by 2022 Green Convergence Professional Manpower Training Program of the Korea Environmental Industry and Technology Institute funded by the Ministry of Environment.

Hand-Print method for preparation of large area and binder free electrodes for photodetection and electrocatalytic hydrogen evolution

Modern life is gravitating toward the light harvesting and clean energy production route because fossil fuels are becoming obsolete, which propels the researcher and scientific community to requirements of future photo-sensing and energy inventive devices based on two dimensional (2D) nanomaterials. Herein, we present the fabrication of a flexible film of Ag decorated WSe2 on a paper substrate for visible light (390–780 nm) photodetection and electrocatalysis for hydrogen evolution reaction (HER). A facile handprint technique, and drop cast methods were used without the use of binders and toxic liquids. The photodetector advocates the photoresponsivity (0.43 mA/W) and a specific detectivity (2.9 × 108 Jones) at 780 nm at a low bias of 1.0 V. The WSe2/Ag catalyst film requires an overpotential of −341 mV for HER at a current density of −10 mA/cm2, which is significantly lower than pristine WSe2. The stability of the WSe2/Ag electrode for a long time interval of 15 h indicates chemical robust behavior towards HER reaction. This research opens up the versatile possibility of energy harvesting, and photoconductive devices based on heterostructures.

Liquid phase exfoliated ReS2 nanocrystals on paper based electrodes for hydrogen evolution and supercapacitor applications

Liquid phase exfoliated transition metal dichlcogenides have been considered as promising electrode materials for high performance electrocatalysts for water splitting and pseudocapacitors because they offer higher electrochemical activity than the bulk crystals owing to high concentration of edge active sites. The system model of binder-free electrode architecture is an expedient approach for enhancing the endurance of electrochemical supercapacitors. Herein, we report the flexible, large area and robust paper-based electrode functionalised by electrochemically active 1T-rehenium disulphide (ReS2) nanocrystals. 1T-ReS2 nanocrystals on cellulose paper electrode was used as binder free electrode that exhibits the low over potential of 170 mV and stable charge transport for 14 h. Extremely low series resistance of 2 Ω and charge transfer resistance of 5 Ω are achieved for electrically and electrochemically conducting electrodes. The high catalytic activity originates due to the S-atom. Paper based electrode also exhibits high specific capacitance of 133.0 F g–1 at scan rate of 2 mV s–1 and 124.1 F g–1 at 1 A g–1. Encouragingly, electrode demonstrate the retention of capacitance of more than 95% after 3000 cycles with advantage of being light weight. This research paves the foundation for the expansion of large-scale active catalysts using an intrinsic charge engineering approach. Structural and electronic properties are studied by first principles calculation.

Realizing Efficient Photoelectrochemical Performance for Well-Designed CdS@ZnIn2S4 Heterostructure Photoanode with Directional Interfacial Charge Transfer Dynamics

Designing a heterostructure photoanode with an appropriate band alignment, a beneficial charge migration pathway, and an adequate interfacial coupling is crucial for photoelectrochemical (PEC) energy conversion. Herein, we fabricate a hetero-nanostructure photoanode with CdS nanorods (CdS NRs) and two-dimensional (2D) ZnIn2S4 nanosheets (ZIS NSs) via a two-step in situ growth method on FTO glass to acquire a sufficient interfacial contact between two semiconductors. Based on their electronic band structures, the CdS is designed to be firstly grown on FTO to act as a photoelectron transport layer and 2D ZIS is further fabricated on the CdS as a photohole accumulation layer to directly contact the electrolyte. Benefitting from the Type II band alignment between the CdS and ZIS, such a heterostructure significantly enhances the separation efficiency and prolongs the lifetime of photocarriers. More importantly, it ensures that photoholes accumulate on the 2D ZIS with a highly exposed surface area for an oxidation reaction at the surface-active sites, while the photoelectrons transfer to counter electrode for hydrogen evolution. The optimum CdS@ZIS heterostructure photoanode exhibits a superior PEC performance with a photocurrent of 4.19 mA/cm2 at 1.23 VRHE (two times that of the CdS and eight times that of ZIS) and an applied bias photo-to-current efficiency (ABPE) of 1.93% at 0.49 VRHE. This work can inspire the future design of heterostructure photoanodes for highly efficient solar energy conversion.