Heterostructure Electrocatalyst Research Articles

Interfacial engineering of two-dimensional NiS2/VS heterostructure nanosheets as bifunctional electrocatalysts for urea-assisted energy-saving water electrolysis

Heterostructure electrocatalysts based on transition metal sulfides (TMS) have been extensively applied in renewable energy research because the rich interfaces afford high intrinsic activities for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, we have fabricated two-dimensional (2D) nickel sulfide and vanadium sulfide heterojunction nanosheets (NiS2/VS-3:1) arranged on carbon cloth as efficient bifunctional catalysts for electrocatalytic water splitting. The strong electronic interaction between NiS2 and VS in the NiS2/VS-3:1 heterostructure nanosheets was beneficial to tune the electronic structures and induce the formation of dual-functional reactive sites (Ni3+ for OER and V2+ for HER) in one heterojunction electrocatalyst, contributing to the promising catalytic activities toward electrocatalytic water splitting. The NiS2/VS-3:1 electrocatalyst has exhibited prominent catalytic activities toward HER and OER, which required low overpotentials of 74 and 235 mV to yield the current density of 10 mA cm−2 in 1 M KOH. Compared with pure NiS2 or VS, the NiS2/VS-3:1 electrocatalyst delivered faster reaction kinetics, improved electron-transfer ability, and enlarged electrochemical active surface area, which were mainly attributed to the fascinating heterostructure in the nanosheets. Some more easily oxidized substances have been added into electrolyte as adjuvants to realize energy-saving hydrogen production, pollutant degradation, and biomass upgrading.

Synergistic interface engineering and structural optimization over hydroxide-phosphide nanoarray electrocatalysts for efficient alkaline water electrolysis

Developing transitional metal-based electrocatalysts with outstanding oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance is essential for energy-efficiency alkaline water electrolysis. Herein, a group of heterostructured electrocatalysts constructing of nickel-based hydroxide (NiX(OH)x, X = Co, Fe) nanosheets decorated on copper phosphide nanowires arrays，were fabricated. Both of the as-prepared NiCo(OH)x-CuP/CF and NiFe(OH)x-CuP/CF present outstanding HER and OER activity, with the overpotential of 79 and 202 mV to deliver 10 mA cm−2, respectively, along with considerable long-term stability. Encouragingly, the NiCo(OH)x-CuP/CF ǀǀ NiFe(OH)x-CuP/CF couple enables sustainable alkaline water electrolysis and powered by a solar-powered system. In-depth analyses elucidate that owing to the modulated heterogeneous interfacial states, both of the catalytic kinetics can be optimized targeting HER and OER, respectively. More significantly, a regulated electrode-electrolyte microenvironment induced by unique arrays nanostructure efficiently promote the electron-mass transfer capacity, thereby facilitating the catalytic activity expression. This work demonstrates the desirable catalytic performance by rationally designing of hydroxide-phosphide heterostructure, and highlights the structural features on catalytic performance promotion.

Sulfur scrambling assisted in-situ growth of 3D - hierarchical FeNi2S4@Mo-doped Ni3S2/NF nanosheet arrays: A stellar performer towards alkaline water electrolysis

Industrial alkaline water electrolysis is facing major difficulties in developing inexpensive, abundant and active bifunctional non-noble metal electrocatalysts. Herein, a heterogeneous three-dimensional (3D) FeNi2S4@Mo-doped Ni3S2/NF heterostructure electrocatalyst is synthesized by a controlled two-step hydrothermal method. Based on the unique structural advantages, the number of redox active sites and the conductivity of the heterostructure electrode are improved remarkably resulting the shortening of ion diffusion path, effective penetration of the electrolyte and decrease in equivalent series resistance. The electrode achieves 10 mA cm−2 current density in hydrogen evolution reaction and oxygen evolution reaction at ∼121 and 150 mV overpotential, respectively in alkaline solution. The bifunctional electrochemical performance of the heterostructure is confirmed from the low cell voltage of 1.501 V and higher stability in overall water electrolysis. This work provides a useful strategy to tune the electrocatalytic performance by doping engineering and hetero-interface formation that offers an efficient self-supported 3D heterostructure electrode material for overall water electrolysis.

Collaborative Interface Optimization Strategy Guided Ultrafine RuCo and MXene Heterostructure Electrocatalysts for Efficient Overall Water Splitting.

Developing highly active and robust electrocatalysts for the hydrogen/oxygen evolution reaction (HER/OER) is crucial for the large-scale utilization of green hydrogen. In this study, a collaborative interface optimization guided strategy was employed to prepare a metal-organic framework (MOF) derived heterostructure electrocatalyst (MXene@RuCo NPs). The obtained electrocatalyst requires overpotentials of only 20 mV for the HER and 253 mV for the OER to deliver a current density of 10 mA/cm2 in alkaline media, respectively, and it also exhibits great performance at high current density. Experiments and theoretical calculations reveal that the doped Ru introduces second active sites and decreases the diameter of nanoparticles, which greatly enhances the number of active sites. More importantly, the MXene/RuCo NPs heterogeneous interfaces in the catalysts exhibit great synergistic effects, decreasing the work function of the catalyst and improving the charge transfer rate, thus reducing the energy barrier of the catalytic reaction. This work represents a promising strategy for the development of MOF-derived highly active catalysts to achieve efficient energy conversion in industrial applications.

Ion-sharing interface and directional doping synergize N-MoS2/Se-CoS2 catalyst for efficient hydrogen evolution

Interfacing and doping can effectively harmonize the electronic and coordination states of active centers in the electrocatalysts. Herein, we prepare heterostructured N-MoS2/Se-CoS2 electrocatalyst with ion-sharing interfaces and directional doping to activate inert basal phases for hydrogen evolution reaction (HER). Based on experimental and theoretical results, their synergistic effects on electron redistribution, electronic structure and coordination chemistry are investigated; furthermore, roles of each component and bridged Mo-S-Co sites at the phase interfaces as active sites in optimizing the adsorption/desorption of essential reaction intermediates H* and OH–, as well as the free energies of unit reaction steps in the HER, are elucidated in depth. The N-MoS2/Se-CoS2 catalyst needs only 37 mV to give current density of 10 mA cm−2 with a low Tafel slope of 49.4 mV dec−1; more importantly, the catalyst delivers a long-term durability for HER in alkaline condition and comparable performance with commercial RuO2||Pt/C system in a two-electrode assembled electrolyzer. This work provides more insights into the design and preparation of high-performance heterostructured electrocatalysts.

Flake-like B13P2-Na2B4O7 heterostructure electrocatalyst for hydrogen evolution reaction

The heterostructure catalysts with the larger surface area are expected to show improved electrocatalytic activity for hydrogen evolution reaction (HER). Herein, B13P2-Na2B4O7 heterostructure catalysts were synthesized via vacuum annealing at distinct temperatures, and their electrocatalytic activity towards HER was investigated. The electrocatalyst synthesized at 700 °C (NB 700) demonstrated superior HER performance, showing an overpotential of 65, 170, and 230 mV at −10, −50, and −100 mA cm−2. With a low Tafel slope of 82 mV dec-1, the NB 700 demonstrates faster charge transfer kinetics in alkaline media. This work gives insight into exploring various heterostructure electrocatalysts involving phosphides for commercial hydrogen production.

Interface engineering assisted Fe-Ni3S2/Ni2P heterostructure as a high-performance bifunctional electrocatalyst for OER and HER

Rational development and construction of electrochemical water splitting catalysts with excellent activity and super-durability utilizing earth-abundant elements are extremely desirable and imperative for energy crisis. Herein, a self-supported hierarchical Fe-doped nickel sulfide/nickel phosphide (nanoflower-linked nanosheet arrays grown vertically on nickel foam) heterostructure electrocatalyst was obtained via a successive structural transformation to realize high-efficiency alkaline OER and HER performance. Benefiting from the novel nanoflower-sheet crosslinked structure on NF, electronic coupling reconstruction and abundant edge sites, as-synthesized Fe-Ni3S2/Ni2P electrocatalyst exhibits remarkable electrocatalytic OER and HER activity in both low and high current density regions. Specifically, the Fe-Ni3S2/Ni2P electrode achieved low overpotentials of 172, 277 and 357 mV at current densities of 10, 50 and 100 mA·cm−2 for OER, respectively. A series of experimental results confirmed that the surface reconfiguration behavior of Fe-Ni3S2/Ni2P heterostructure led to the formation of amorphous M-OH bond system, which was answerable to the prominent OER catalyst properties. This work confirms the potential of designing robust bifunctional electrocatalysts for alkaline water electrocatalysis by carefully combining doping engineering as well as interfacial effects.

Synergistic Effect of P Doping and Mo-Ni-Based Heterostructure Electrocatalyst for Overall Water Splitting.

Heterostructure construction and heteroatom doping are powerful strategies for enhancing the electrolytic efficiency of electrocatalysts for overall water splitting. Herein, we present a P-doped MoS2/Ni3S2 electrocatalyst on nickel foam (NF) prepared using a one-step hydrothermal method. The optimized P[0.9mM]-MoS2/Ni3S2@NF exhibits a cluster nanoflower-like morphology, which promotes the synergistic electrocatalytic effect of the heterostructures with abundant active centers, resulting in high catalytic activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolyte. The electrode exhibits low overpotentials and Tafel slopes for the HER and OER. In addition, the catalyst electrode used in a two-electrode system for overall water splitting requires an ultralow voltage of 1.42 V at 10 mA·cm-2 and shows no obvious increase in current within 35 h, indicating excellent stability. Therefore, the combination of P doping and the heterostructure suggests a novel path to formulate high-performance electrocatalysts for overall water splitting.

Structural control of heterostructured Co3N-Co nano-corals for boosting electrocatalytic hydrogen evolution based on insulator-confined plasma engineering

A facile phase reconfiguration has been considered as an essential issue in achieving heterostructures for boosting the electrocatalytic H2 production. Compared to chemical approaches, plasma-based technique serves as a favorable strategy to achieve hetero-structured nano-frameworks, but its modulation on nano-structured precursor inevitably leads to multi-step fabrication process and it is difficult to precisely control the partial surface modulation through plasma technique due to complicated interaction environment. To achieve heterostructures with optimized hydrogen evolution reaction (HER) behavior, we design a novel auxiliary insulator-confined plasma system to directly achieve Co3N-Co heterostructure (hCNC) with favorable activity by controlling surface heating process during plasma nitridation. The resultant hCNC nano-framework delivers excellent catalytic performance, evidenced by its overpotential of 97 and 229 mV at current density of 10 and 100 mA cm−2 for HER in alkaline condition, in stark comparison with that of normal plasma fabricated Co3N. Operando plasma diagnostics along with numerical simulation further confirm the effect of surface heating on typical plasma parameters as well as the Co3N-Co nano-structure, indicating the key factor responsible for the high-performance hetero-structured electrocatalyst.

Engineering Cu/NiCu LDH Heterostructure Nanosheet Arrays for Highly-Efficient Water Oxidation.

The development of stable and efficient electrocatalysts for oxygen evolution reaction is of great significance for electro-catalytic water splitting. Bimetallic layered double hydroxides (LDHs) are promising OER catalysts, in which NiCu LDH has excellent stability compared with the most robust NiFe LDH, but the OER activity is not satisfactory. Here, we designed a NiCu LDH heterostructure electrocatalyst (Cu/NiCu LDH) modified by Cu nanoparticles which has excellent activity and stability. The Cu/NiCu LDH electrocatalyst only needs a low over-potential of 206 mV and a low Tafel slope of 86.9 mV dec-1 at a current density of 10 mA cm-2 and maintains for 70 h at a high current density of 100 mA cm-2 in 1M KOH. X-ray photoelectron spectroscopy (XPS) showed that there was a strong electronic interaction between Cu nanoparticles and NiCu LDH. Density functional theory (DFT) calculations show that the electronic coupling between Cu nanoparticles and NiCu LDH can effectively improve the intrinsic OER activity by optimizing the conductivity and the adsorption energy of oxygen-containing intermediates.

A review on metallic carbides/phosphides embedded in N-doped porous carbon as highly efficiency electrocatalyst for hydrogen evolution reactions in alkaline medium

The designing of electrocatalyst to perform hydrogen evolution reaction (HER) in alkaline medium is presently a demanding pathway for sustainable production of hydrogen (H2) which can be generated from alkaline water electrolysis used in industries. Although a large number of electrocatalyst reported in literature have the tendency to exhibit superior HER performance in acidic medium, but the vaporization of acid electrolyte causes corrosion of the cell and resulted in contamination during the H2 production. The involvement of additional step during water dissociation process (volmer step) in alkaline medium could cause serious sluggish electrode kinetics and thus a hunt of new type of heterostructured electrocatalyst (to indue strong synergetic effect of the heterointerfaces) to outperform noble precious metals are under exploration. The development of earth abundant transition metal carbides/phosphides have been emerging recently because of their electronic structure/configuration are similar to that of platinum (Pt), leading to enhance the elecrocatalytic performance. A variety of metallic carbides/phosphides incorporated on porous materials are studied by researchers are faced difficulty in integration of single nanostructure unit to achieve HER activity in alkaline medium as same as that in acidic medium. The present review aims to provide comprehensive of heterostructured carbides/phosphides supported on N-doped porous carbon (NPC) for electrocatalytic efficiency for HER. We also discussed the influencing role of structure, codopants, and the porosity for lowering overpotentials. Finally, the challenges and the future goals for designing efficient electrocatalyst to provide promising HER for large scale applications are highlighted.

Core-shell Fe/Fe3C heterostructure@carbon layers anchored on N-doped porous carbon for boosting oxygen reduction reaction

It is still challenging but crucial to plumb non-noble metal-based oxygen reduction reaction (ORR) catalysts with comparable or better performance than benchmark Pt/C catalysts. Herein, we proffer an unconventional core-shell-structured iron-based heterostructure electrocatalyst constructed by a Fe/Fe3C heterostructure nanoparticle core wrapped by a graphitic shell embedded on a conductive N-doped mesoporous graphite skeleton (Fe/Fe3C@NC) via facile pyrolysis of MIL-53(Fe) (MIL = Matérial Institute Lavoisier) and melamine. The Fe/Fe3C@NC catalyst delivers more positive half-wave potential (E1/2) of 0.86 V and a low Tafel slope of 56 mV dec−1 for ORR, outpacing the benchmark Pt/C catalyst, and it also shows remarkable long-term durability and excellent methanol tolerance. The marvelous ORR behaviors can be attributed to its distinctive morphologic structure: the heterostructure can enhance intrinsic ORR activity; the core-shell nanostructure can enhance ORR activities through unique electron transfer between iron species and their conductive carbon shells, which can also act as protective barriers to ensure long-term stability; the high-content pyridinic-N doping can be used as additional active centers; and the abundant mesopores facilitate the diffusion of electrolyte, which can further upgrade ORR activities. This study proffers a strategy to design and fabricate non-noble catalysts with well-designed nanoarchitecture and high catalytic activity.

Heterostructured Ultrathin Two-Dimensional Co-FeOOH Nanosheets@1D Ir-Co(OH)F Nanorods for Efficient Electrocatalytic Water Splitting

It is highly desirable to develop high-performance and robust electrocatalysts for overall water splitting, as the existing electrocatalysts exhibit poor catalytic performance toward hydrogen and oxygen evolution reactions (HER and OER) in the same electrolytes, resulting in high cost, low energy conversion efficiency, and complicated operating procedures. Herein, a heterostructured electrocatalyst is realized by growing Co-ZIF-67-derived 2D Co-doped FeOOH on 1D Ir-doped Co(OH)F nanorods, denoted as Co-FeOOH@Ir-Co(OH)F. The Ir-doping couples with the synergy between Co-FeOOH and Ir-Co(OH)F effectively modulate the electronic structures and induce defect-enriched interfaces. This bestows Co-FeOOH@Ir-Co(OH)F with abundant exposed active sites, accelerated reaction kinetics, improved charge transfer abilities, and optimized adsorption energies of reaction intermediates, which ultimately boost the bifunctional catalytic activity. Consequently, Co-FeOOH@Ir-Co(OH)F exhibits low overpotentials of 192/231/251 and 38/83/111 mV at current densities of 10/100/250 mA cm-2 toward the OER and HER in a 1.0 M KOH electrolyte, respectively. When Co-FeOOH@Ir-Co(OH)F is used for overall water splitting, cell voltages of 1.48/1.60/1.67 V are required at current densities of 10/100/250 mA cm-2. Furthermore, it possesses outstanding long-term stability for OER, HER, and overall water splitting. Our study provides a promising way to prepare advanced heterostructured bifunctional electrocatalysts for overall alkaline water splitting.

Enhanced electrocatalytic performance for oxygen evolution reaction via active interfaces of Co3O4 arrays@FeO x /Carbon cloth heterostructure by plasma-enhanced atomic layer deposition

Oxygen evolution reaction (OER) is a necessary procedure in various devices including water splitting and rechargeable metal-air batteries but required a higher potential to improve oxygen evolution efficiency due to its slow reaction kinetics. In order to solve this problem, a heterostructured electrocatalyst (Co3O4@FeO x /CC) is synthesized by deposition of iron oxides (FeO x ) on carbon cloth (CC) via plasma-enhanced atomic layer deposition, then growth of the cobalt oxide (Co3O4) nanosheet arrays. The deposition cycle of FeO x on the CC strongly influences the in situ growth and distribution of Co3O4 nanosheets and electronic conductivity of the electrocatalyst. Owing to the high accessible and electroactive areas and improved electrical conductivity, the free-standing electrode of Co3O4@FeO x /CC with 100 deposition cycles of FeO x exhibits excellent electrocatalytic performance for OER with a low overpotential of 314.0 mV at 10 mA cm−2 and a small Tafel slope of 29.2 mV dec−1 in alkaline solution, which is much better than that of Co3O4/CC (448 mV), and even commercial RuO2 (380 mV). This design and optimization strategy shows a promising way to synthesize ideally designed catalytic architectures for application in energy storage and conversion.

Interfacial Engineering of Ni/Ni0.2Mo0.8N Heterostructured Nanorods Realizes Efficient 5-Hydroxymethylfurfural Electrooxidation and Hydrogen Evolution.

Simultaneously achieving electrochemical conversion of biomass-derived molecules into value-added products and energy-efficient hydrogen production is a highly attractive strategy but challenging. Herein, we reported a heterostructured Ni/Ni0.2Mo0.8N nanorod array electrocatalyst deposited on nickel foam (Ni/Ni0.2Mo0.8N/NF), which exhibited excellent electrocatalytic activity toward 5-hydroxymethylfurfural (HMF) oxidation, and nearly 100% conversion of HMF and 98.5% yield of 2,5-furandicarboxylic acid (FDCA) products can be achieved. The post-reaction characterizations unveil that Ni species in Ni/Ni0.2Mo0.8N/NF would be readily converted to NiOOH as the real active sites. Furthermore, a two-electrode electrolyzer was assembled with Ni/Ni0.2Mo0.8N/NF utilized as a bifunctional electrocatalyst for both the cathode and anode, giving rise to a low voltage of 1.51 V to concurrently produce FDCA and H2 at 50 mA cm-2. This work enlightens the significance of regulating redox activities of transition metals via interfacial engineering and constructing heterostructured electrocatalysts toward more efficient energy utilization.

Promoting electrochemical ammonia synthesis by synergized performances of Mo2C-Mo2N heterostructure.

Hydrogen has become an indispensable aspect of sustainable energy resources due to depleting fossil fuels and increasing pollution. Since hydrogen storage and transport is a major hindrance to expanding its applicability, green ammonia produced by electrochemical method is sourced as an efficient hydrogen carrier. Several heterostructured electrocatalysts are designed to achieve significantly higher electrocatalytic nitrogen reduction (NRR) activity for electrochemical ammonia production. In this study, we controlled the nitrogen reduction performances of Mo2C-Mo2N heterostructure electrocatalyst prepared by a simple one pot synthesis method. The prepared Mo2C-Mo2N0.92 heterostructure nanocomposites show clear phase formation for Mo2C and Mo2N0.92, respectively. The prepared Mo2C-Mo2N0.92 electrocatalysts deliver a maximum ammonia yield of about 9.6μgh-1 cm-2 and a Faradaic efficiency (FE) of about 10.15%. The study reveals the improved nitrogen reduction performances of Mo2C-Mo2N0.92 electrocatalysts due to the combined activity of the Mo2C and Mo2N0.92 phases. In addition, the ammonia production from Mo2C-Mo2N0.92 electrocatalysts is intended by the associative nitrogen reduction mechanism on Mo2C phase and by Mars-van-Krevelen mechanism on Mo2N0.92 phase, respectively. This study suggests the importance of precisely tuning the electrocatalyst by heterostructure strategy to substantially achieve higher nitrogen reduction electrocatalytic activity.

Ultrathin NiO/Ni3S2 Heterostructure as Electrocatalyst for Accelerated Polysulfide Conversion in Lithium–Sulfur Batteries

The practical application of Lithium–Sulfur batteries largely depends on highly efficient utilization and conversion of sulfur under the realistic condition of high‐sulfur content and low electrolyte/sulfur ratio. Rational design of heterostructure electrocatalysts with abundant active sites and strong interfacial electronic interactions is a promising but still challenging strategy for preventing shuttling of polysulfides in lithium–sulfur batteries. Herein, ultrathin nonlayered NiO/Ni3S2 heterostructure nanosheets are developed through topochemical transformation of layered Ni(OH)2 templates to improve the utilization of sulfur and facilitate stable cycling of batteries. As a multifunction catalyst, NiO/Ni3S2 not only enhances the adsorption of polysulfides and shorten the transport path of Li ions and electrons but also promotes the Li2S formation and transformation, which are verified by both in‐situ Raman spectroscopy and electrochemical investigations. Thus, the cell with NiO/Ni3S2 as electrocatalyst delivers an area capacity of 4.8 mAh cm−2 under the high sulfur loading (6 mg cm−2) and low electrolyte/sulfur ratio (4.3 μL mg−1). The strategy can be extended to 2D Ni foil, demonstrating its prospects in the construction of electrodes with high gravimetric/volumetric energy densities. The designed electrocatalyst of ultrathin nonlayered heterostructure will shed light on achieving high energy density lithium–sulfur batteries.

Achieving balanced behavior between polysulfides adsorption and catalytic conversion from heterostructure Fe3C-Fe3P promotor for high-performance lithium-sulfur batteries

Although rechargeable lithium-sulfur batteries (LSBs) are next generation energy storage devices, severe shuttle effect and sluggish multi-electron redox reactions compromise the practical application of LSBs. To address these issues and enable the manufacture of robust LSBs, here the use of Fe3C-Fe3P heterostructure encapsulated in nitrogen–doped carbon nanotubes (FeCP@NCNT) was synthesized. The tubular geometry of FeCP@NCNT provided buffering void to suppress volume change, and afforded conductive network to expedite the diffusion of Li+, as well as endowed plenteous active sites to absorb and catalyze the transformation of LiPSs during charge–discharge cycles. Experimental data proved that FeCP@NCNT could strengthen the “anchoring of lithium polysulfides (LiPSs)” (by Fe3P) and expedite the “diffusion of intermediate” (by CNT) as well as accelerate the “catalytic phase conversion” (by Fe3C), resulting in balanced “trapping-diffusion-conversion” dynamic process. Notably, FeCP-3 h@NCNT/G/S attained an initial capacity of 1127 mAh/g with a low decay rate of 0.12 % at 1C for 300 cycles Moreover, FeCP-3 h@NCNT/G/S delivered excellent battery performances under high currents of 2 and 5C for 500 cycles. This work felicitously proposed the strategy to fabricate metal carbide-phosphide heterostructure electrocatalyst for high-performance LSBs.

Defect-rich high-entropy oxide nanospheres anchored on high-entropy MOF nanosheets for oxygen evolution reaction

In this work, high-entropy oxide nanoparticles (HEO NPs)/high-entropy metal-organic framework (HE-MOF) heterostructure electrocatalysts for oxygen evolution reaction (OER) are constructed by in-situ growth of HEO NPs on HE-MOF using partial-localized pyrolysis strategy, and the effect of pyrolysis temperature on the OER performance are studied. The results indicate that the well-dispersed HEO NPs are rich in defects such as oxygen vacancy and lattice distortion, which can increase catalytic active centers. Meanwhile, the nanosheet-like HE-MOF not only acts as the support HEO NPs catalyst but also is kinetically beneficial for fast electrons and ions transportation. Among all the prepared nanostructures, HE-MOF-350-200 shows the best OER performance, achieving a low overpotential of 266 mV at 50 mA cm−2 along with a satisfactory stability.

Regulating Complex Transition Metal Oxyhydroxides Using Ni3S2: 3D NiCoFe(oxy)hydroxide/Ni3S2/Ni Foam for an Efficient Alkaline Oxygen Evolution Reaction

In electrochemical decomposition of water, the slow kinetics of the anodic oxygen evolution reaction (OER) is a challenge for efficient hydrogen production. Heterointerface engineering is a desirable way to rationally design electrocatalysts for the OER. Herein, we designed and fabricated a nanoparticle flower-like NiCoFe(oxy)hydroxide catalyst in situ grown on the surface of Ni3S2/NF to construct a heterojunction via combining hydrothermal and electrodeposition methods. The heterostructure exhibits a smaller overpotential of 254 mV at a large current density of 100 mA cm-2 in 1 M KOH than that of pristine NiCoFeOxHy/NF (356 mV) and Ni3S2/NF (471 mV). Tafel and electrochemical impedance spectroscopy further showed a favorable kinetics during electrolysis. The role of the substrate Ni3S2 was explored via density functional theory calculations. Our calculations found that SOx on the Ni3S2 surface is a strong nucleophilic group and the synergy effect between Fe and SOx could break *OOH to reduce the Gibbs energy. We also found that the contribution of SOx in sulfates to the OER activity could be negligible. Furthermore, a series of comparative samples were prepared to test this synergy effect. Our experiments indicated that the introduction of Ni3S2 is beneficial. The present contribution provides an important helpful insight into the design and fabrication of novel and highly efficient heterostructure electrocatalysts by introducing nucleophilic groups at the interface.