Enriched oxygen vacancy promoted heteroatoms (B,P, N,and S) doped CeO2: Challenging electrocatalysts for oxygen evolution reaction (OER) in alkaline medium

Increasing worldwide energy consumption has prompted considerable study into energy generation and energy storage systems in recent years. Chemical fuels may be produced efficiently via electrocatalytic water splitting, which uses electric and solar power. The development of efficient anodic electrocatalysts for efficient oxygen evolution reaction (OER) is a greater concern of present energy research. Cerium oxide (CeO₂) are promising electrocatalysts that exhibit outstanding OER but their reduced stability obstructs the practical application. A novel strategy was established to construct an effective catalyst of heteroatom (N, B, P and S) doped CeO₂ matrix were prepared. Moreover, the doping of heteroatoms into the CeO₂ matrix processes the improved electronic conductivity, reactive sites, increases the electrochemical catalytic activity, which enhances the water oxidation reaction. Consequently, well-suited alkaline electrolysers were brought together for water oxidation to ideal OER electrocatalytic activity. The OER activity of the electrocatalysts follows the order of S–CeO₂ (190 mV@10 mA cm⁻²), N– CeO₂ (220 mV @10 mA cm⁻²), P– CeO₂ (230 mV @10 mA cm⁻²), B–CeO₂ (250 mV @10 mA cm⁻²) and CeO₂ (260 mV @10 mA cm⁻²) in 1 M of KOH. From the kinetics analysis, Tafel slope value achieved for catalysts CeO₂, B–CeO_2, P–CeO₂, N–CeO₂ and S–CeO₂ are 142 mV dec⁻¹,121 mV dec⁻¹, 102 mV dec⁻¹, 98 mV dec⁻¹ and 83 mV dec⁻¹ respectively. These results validate that the S–CeO₂ electrode is prominent for OER performance with the requirement of cell voltage of 1.42 V at 10 mA cm⁻² current density. In addition, sulphur doped CeO₂ relatively have excellent stability through chrono-potentiometric analysis lasting for 20 h. Although the heteroatoms doped CeO₂ is acts as anode material, the preparation method is widespread, which will reduce the synthesis cost and streamline the preparation of electrode for OER. This research effort delivers a complete advantage for the development of robust, environmentally friendly and highly dynamic electrocatalysts for OER activity.     

Facile synthesis of three-dimensional spherical Ni(OH)2/NiCo2O4 heterojunctions as efficient bifunctional electrocatalysts for water splitting

Synthesis of highly efficient, non-noble and bi-functional electrocatalysts is exceedingly challenging and necessary for water splitting devices. In this work, three-dimensional spherical Ni(OH)₂/NiCo₂O₄ heterojunctions are prepared by a one-step hydrothermal method and the hybrids are explored as efficient electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in an alkaline electrolyte via tuning different Ni/Co atomic ratios of heterojunctions. The optimized Ni(OH)₂/NiCo₂O₄ (S (1:1)) exhibits high electrocatalytic activity with an ultralow over-potential of 189 mV at 10 mA cm⁻² for the HER. With regard to the OER, the over-potential of the as-synthesized S (1:1) heterojunction is only 224 mV at the current density of 10 mA cm⁻². The improved catalytic performance of the Ni(OH)₂/NiCo₂O₄ heterojunctions is attributed to the chemical synergic combining of Ni(OH)₂ and NiCo₂O₄, large specific surface area for exposing more accessible active sites, and heterointerface for activating the intermediates that facilitates electron/electrolyte transport. The prepared catalyst exhibits good durability and stability in HER and OER catalyzing conditions. This study provides a feasible approach for the building of highly efficient bifunctional water splitting electrocatalysts and stimulates the development of renewable energy conversion and storage devices.     

In situ grown Cu-Based metal-organic framework on copper foam as high-performance electrocatalysts for oxygen evolution reaction

It is of great significance to develop highly efficient and robust oxygen evolution reaction (OER) electrocatalysts derived from earth-abundant and inexpensive elements for future hydrogen economy via electrochemical water splitting. Herein, Cu-based metal-organic framework (MOF) is directly supported on conductive Cu foam (CF) by a simply chemical oxidation of Cu substrate to grow Cu(OH)₂ nanowire arrays, followed by solvothermal treatment to obtain in situ grown Cu-based MOF electrode (MOF [Cu(OH)₂]/CF). The as-prepared 3D electrode shows superior OER activity with a low potential of 330 mV to deliver a current density of 10 mA cm⁻², a Tafel slope of 108 mV dec⁻¹, and excellent durability in alkaline media (1.0 M KOH). After electrolysis, XRD confirms that the initial MOFs have been transformed into CuO species, which are essentially active components for OER performance. This demonstrates that the MOFs can serve as efficient precursors for formation of highly active Cu oxide catalysts towards OER. This work provides a new strategy to develop MOFs-derived electrocatalysts for future clean energy conversion and storage systems.     

Highly active atomic Cu catalyst anchored on superlattice CoFe layered double hydroxide for efficient oxygen evolution electrocatalysis

Developing active, natural abundant and non-expensive electrocatalysts for large scale production and storage of clean hydrogen (H₂) fuel is a prerequisite to drive stable water splitting reaction. Herein, atomic Cu species loaded on hierarchical flower-like CoFe layered double hydroxides (LDHs) superlattice (denoted as Cu_x/CoFe LDHs) were firstly fabricated by a facile co-precipitation method followed by a room temperature treatment to load the atomic Cu species from alkaline copper salt solution. The superlattice structure was proved by the high resolution transmission electron microscopy (HRTEM). Remarkably, benefiting from high level long ordering associated with vacant cation sites and defects, the unique superlattice structural features and the atomic Cu % loading onto the LDHs matrix, the obtained Cu_x/CoFe LDHs electrocatalyst exhibited superior activity and stability for oxygen evolution reaction (OER). The loaded atomic Cu species improves the electronic structure and provides more exposed active sites due to synergetic electron coupling between Copper and the LDHs. These atomic species have outstanding potentials for achieving high selectivity and reactivity in electrocatalysis and heterocatalysis. Importantly, the efficient resulted Cu_4.76/CoFe LDHs electrode in which the atomic Cu % loading ratio is 4.76% showed the best electrocatalytic activity which only required the much lower overpotential of 253 mV to reach 10 mA/cm² and a small Tafel slope of 63 mV/decade in 1 M KOH. This electrocatalyst possessed unique superior features to many other state-of-the-art earth-abundant electrocatalysts. This work paves a facile and novel method for enhancing the catalytic activity of CoFe LDHs based electrocatalyst, which may be extended to the synthesis of future electrocatalysts having highly active OER performance.     

Cu2S@NiFe layered double hydroxides nanosheets hollow nanorod arrays self-supported oxygen evolution reaction electrode for efficient anion exchange membrane water electrolyzer

Herein, we prepared highly active self-supported Cu₂S@NiFe layered double hydroxides nanosheets (LDHs) oxygen evolution reaction (OER) electrode (Cu₂S@NiFe LDHs/Cu foam) with three-dimensional (3D) multilayer hollow nanorod arrays structure, which is composed of the outer layer (two-dimensional (2D) NiFe LDHs) and the inner layer (one-dimensional (1D) Cu₂S hollow nanorod arrays). The unique structure of NiFe LDHs and Cu₂S hollow nanorod composites can expose more active sites, and simultaneously promote electrolyte penetration and gas release during the water electrolysis process. Thus, the Cu₂S@NiFe LDHs/Cu foam electrode exhibits a significant OER performance, with the overpotentials of 230 and 286 mV at 50 and 100 mA cm⁻², respectively. Anion exchange membrane water electrolyzer (AEMWE) with the prepared electrode can attain a voltage of 1.56 V at the current density of 0.50 A cm⁻², showing a good performance that is comparable to the-state-of-the-art AEMWE in 1 M KOH. In addition, the AEMWE can be run for 300 h at the current density of 0.50 A cm⁻². The high performance and good stability of AEMWE are attributed to the special structure of the OER electrode, which can prevent the agglomeration of nanosheets and thus expose more active sites at the edge of the nanosheets.     

Open and porous NiS2 nanowrinkles grown on non-stoichiometric MoOx nanorods for high-performance alkaline water electrolysis and supercapacitor

Hierarchical hybrid heterostructures are regarded to be promising materials for highly efficient bifunctional electrocatalysts and high-performance supercapacitors due to their intriguing morphological features and remarkable electrochemical properties. Herein, we demonstrate the rational construct of cost-effective MoO_x@NiS₂ hybrid nanostructures as bifunctional electrocatalysts and the electrode material of supercapacitor. Microstructural analysis shows that the hybrid is a kind of hierarchical heterostructure composed of open and porous NiS₂ nanowrinkles in situ grown on non-stoichiometric MoO_x nanorods, which greatly improves the conductivity, and effectively maximized the electrochemical surface area. As expected, the MoO_x@NiS₂ hybrid show remarkable electrocatalytic performance in alkaline media, such as overpotentials of 101 mV at 10 mA cm^?2 for hydrogen evolution reaction (HER) and 278 mV at 20 mA cm^?2 for oxygen evolution reaction (OER), and a low cell voltage of 1.62 V to deliver a current density of 10 mA cm^?2. Moreover, the hybrid nanostructures present a high specific capacitance 1050 A/g at 1 A/g with ultra-long stability in 6 M KOH. The strategy proposed here introduces a new perspective about the development of efficient earth-abundant bifunctional elecrocatalysts and electrode materials for superior energy conversion and storage devices.     

Accelerated oxygen evolution kinetics on NiFeAl-layered double hydroxide electrocatalysts with defect sites prepared by electrodeposition

NiFe layered double hydroxides (LDHs) is considered to be one of the LDHs electrocatalyst materials with the best electrocatalytic oxygen evolution properties. However, its poor conductivity and inherently poor electrocatalytic activity are considered to be the limiting factors inhibiting the electrocatalytic properties for oxygen evolution reaction (OER). The amorphous NiFeAl-LDHs electrocatalysts were prepared by electrodeposition with nickel foam as the support, and the D-NiFeAl-LDHs electrocatalyst with defect sites was then obtained by alkali etching. The mechanism of catalysts with defect sites in OER was analyzed. The ingenious defects can selectively accelerate the adsorption of OH⁻, thus enhancing the electrochemical activity. The D-NiFeAl-LDHs electrocatalyst had higher OER electrocatalytic activity than NiFe-LDHs electrocatalyst: its accelerated OER kinetics were mainly due to the introduction of iron and nickel defects in NiFeAl-LDHs nanosheets, which effectively adjusted the surface electronic structure and improved OER electrocatalytic performance. There was only a low overpotential of 262 mV with the current density of 10 mA cm⁻², and the Tafel slope was as low as 41.67 mV dec⁻¹. The OER electrocatalytic performance of D-NiFeAl-LDHs was even better than those of most of the reported NiFe-LDHs electrocatalysts.     

MgO as promoter for electrocatalytic activities of Co3O4–MgO composite via abundant oxygen vacancies and Co2+ ions towards oxygen evolution reaction

Oxygen evolution reaction (OER) is known as bottleneck problem during the water splitting process due to high energy barrier and non-availability of efficient nonprecious electrocatalysts. The cobalt oxide (Co₃O₄) in the spinel phase has limited OER activity and stability in the alkaline media. For this purpose, we have carried out the synthesis of Co₃O₄–MgO (CM) composite by wet chemical method and it offers abundant oxygen vacancies and Co²⁺ concentration for the efficient OER reaction. The effect of different amounts of MgO on the OER activity of Co₃O₄ was also studied. Despite inactivity of MgO towards OER, it creates high density of oxygen vacancies and favored the formation Co²⁺ ions at the surface, thus accelerated the OER kinetics. The physical studies were performed to investigate the morphology, crystalline structure, surface information and chemical composition using several analytical techniques. The optimized CM-0.1 composite produced an overpotential of 274 mV at 10 mAcm⁻² which is lower in value than the pristine Co₃O₄. The significant enhancement in the OER activity was verified by the large value of electrochemical active surface area values 12.8 μFcm⁻² and the low charge transfer resistance of 45.96 Ω for the optimized CM-0.1 composite. The use of abundance materials for the synthesis of CM composite revealed an enhanced OER performance, suggesting the dynamic role of MgO, therefore it could be used for improving the electrochemical properties of extended range of metal oxides for specific application especially energy conversion and storage devices.     

N/C doped nano-size IrO2 catalyst of high activity and stability in proton exchange membrane water electrolysis

It is highly desirable to synthesize and deploy low-cost and highly efficient catalysts for the oxygen evolution reaction (OER) to catalyze water splitting. We show that N/C doped amorphous iridium oxide combines the benefits of nano-size (approximately 2 nm), which results in exposure to large active surface areas and features of oxygen defects, which make for an electronic structure suitable for the OER. Systematic studies indicate that the OER activity of the iridium oxide catalyst is accelerated by the effect of the structure and chemical state of the iridium element. Remarkably, the N/C doped amorphous iridium oxide catalyst shows a lower cell voltage of 1.774 V at 1.5 A cm⁻², compared with IrO₂ (1.847 V at 1.5 A cm⁻²), and it can maintain such a high current density for over 200 h without noticeable performance deterioration. This work provides a promising method for the improving OER electrocatalysts and the construction of an efficient and stable PEM water cracking system.     

Multi-shelled CoS2–MoS2 hollow spheres as efficient bifunctional electrocatalysts for overall water splitting

The exploration of highly efficient non-precious electrocatalysts is essential for water splitting devices. Herein, we synthesized CoS₂–MoS₂ multi-shelled hollow spheres (MSHSs) as efficient electrocatalysts both for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) using a Schiff base coordination polymer (CP). Co-CP solid spheres were converted to Co₃O₄ MSHSs by sintering in air. CoS₂–MoS₂ MSHSs were obtained by a solvothermal reaction of Co₃O₄ MSHSs and MoS₄²⁻ anions. CoS₂–MoS₂ MSHSs have a high specific surface area of 73.5 m²g^-1. Due to the synergistic effect between the CoS₂ and MoS₂, the electrode of CoS₂–MoS₂ MSHSs shows low overpotential of 109 mV with Tafel slope of 52.0 mV dec⁻¹ for HER, as well as a low overpotential of 288 mV with Tafel slope of 62.1 mV dec⁻¹ for OER at a current density of 10 mA cm⁻² in alkaline solution. The corresponding two-electrode system needs a potential of 1.61 V (vs. RHE) to obtain anodic current density of 10 mA cm⁻² for OER and maintains excellent stability for 10 h.     

A highly active oxygen evolution electrocatalyst: Ni-Fe-layered double hydroxide intercalated with the Molybdate and Vanadate anions

Efficient low-cost electrocatalysts in the oxygen evolution reaction (OER) are important components of renewable energy technologies, e.g. solar fuel synthesis and water splitting for powering fuel cells. A great deal of attention has been attracted toward LDHs due to their electrical power and they are potentially applied in the field of electrocatalysts. The present paper reports synthesis of the Ni-Fe-Molybdate and Ni-Fe-Vanadate layered double hydroxides (LDHs) using a simple co-precipitation method. Powder X-ray diffraction, Fourier transform infrared spectra, Transmission electron microscopy, and X-ray energy dispersive spectroscopy spectrum provide successful intercalation of the Vanadate and Molybdate anions. Compared to the bare glassy carbon electrode, in alkaline media, the as-obtained Ni-Fe-MoO₄-LDH represents superior electrocatalytic activity toward water oxidation with the overpotential of 491 mV at10 mA/cm² and a low Tafel slope of 23 mV/dec. Ni–Fe-MoO₄-LDH exhibits good OER activity, which is stated as low onset overpotential, small Tafel slope, and large exchange current density. The current density of the Ni–Fe-MoO₄-LDH nanosheets is about 10 mA cm⁻² at the overpotential of 0.491 (V vs SCE). This value is much larger than that of the Ni–Fe-NO₃-LDH and Ni–Fe-VO₃-LDH nanoparticles.     

Constructing La-doped ultrathin Co-based nanostructured electrocatalysts for high-performance water oxidation process

Constructing highly efficient and low cost electrocatalysts for oxygen evolution reaction (OER) is pivotal to various energy storage and conversion devices. In this work, five different rare earth (RE) metals doped (La, Ce, Pr, Nd, Er) Ag-nanoparticles-decorated α-Co(OH)₂ nanostructured electrocatalysts, which are grown on nickel foam (NF), are successfully prepared by a facile one-step hydrothermal approach. It is found that La-doped 2D ultrathin (～2.0 nm) CoAg nanosheets arrays (denoted as La–CoAg/NF) can demonstrate the highest electrochemical activity towards OER in 1 M KOH solution among these RE-doped electrocatalysts. It delivers the lowest overpotential at 10 mA cm^?2 (233 mV), the smallest Tafel slope (44.3 mV dec^?1) and extraordinary stability for 35 h with no significant change during harsh OER process. The reasons for the enhanced performance may come from unique ultrathin 2D nanostructure and La-induced strong electronic interaction among Co, Ag, and La atoms. This work provides an essential insight to the development of RE-metal doped electrocatalysts for energy conversion.     

Core-shell nanoarray structured La doped Cu(OH)2@NiCo layered double hydroxide for oxygen evolution reaction

Efficient hydrogen production via water splitting is significant because of the zero-carbon emission property. Developing low-cost and highly efficient electrocatalysts for the oxygen evolution reaction (OER), a key half-reaction of water splitting, is critical. Herein, we designed Cu(OH)₂@NiCo layered double hydroxide core-shell nanoarray supported on copper foam (CF) with different La doping amount (abbreviated as Cu(OH)₂@NiCoLa LDH/CF) via the facile electrodeposition method. Owing to the synergistic effect between La and NiCo LDH by electronic structure tuning, Cu(OH)₂@NiCoLa LDH/CF shows excellent OER performance with the lowest overpotential of 254 mV to drive the current density of 10 mA cm^?2 and outstanding long-term durability for 24 h. The idea of doping rare-earth metal into non-noble NiCo-based LDHs core-shell nanoarray structure in this work can inspire the design of other efficient electrocatalysts.     

Co0.85Se on three-dimensional hierarchical porous graphene-like carbon for highly effective oxygen evolution reaction

Designing an efficient, cheap and abundant catalyst for oxygen evolution reaction (OER) is crucial for the development of sustainable energy sources. A novel catalyst which could be a promising candidate for such electrocatalysts is described. Co_0.85Se supported on three-dimensional hierarchical porous graphene-like carbon (HPG) exhibits outstanding catalytic performances for OER in alkaline medium. It is found that the onset overpotential is 311 mV on the Co_0.85Se/HPG electrode, which is more 28 and 41 mV negative than that on the Co/HPG and Co₃O₄/HPG electrodes. What's more, the value of Tafel slope is 61.7 mV dec⁻¹ and the overpotential at the current density of 10 mA cm⁻² is 385 mV on this electrode. The Co_0.85Se/HPG of this work is an appealing electrocatalyst for OER in basic electrolyte.     

MoS2/NiFeS2 heterostructure as a highly efficient electrocatalyst for overall water splitting at high current densities

Searching for efficient, stable and low-cost nonprecious catalysts for oxygen and hydrogen evolution reactions (OER and HER) is highly desired in overall water splitting (OWS). Herein, presented is a nickel foam (NF)-supported MoS₂/NiFeS₂ heterostructure, as an efficient electrocatalyst for OER, HER and OWS. The MoS₂/NiFeS₂/NF catalyst achieves a 500 mA cm⁻² current density at a small overpotential of 303 mV for OER, and 228 mV for HER. Assembled as an electrolyzer for OWS, such a MoS₂/NiFeS₂/NF heterostructure catalyst shows a quite low cell voltage (≈1.79 V) at 500 mA cm⁻², which is among the best values of current non-noble metal electrocatalysts. Even at the extremely large current density of 1000 mA cm⁻², the MoS₂/NiFeS₂/NF catalyst presents low overpotentials of 314 and 253 mV for OER and HER, respectively. Furthermore, MoS₂/NiFeS₂/NF shows a ceaseless durability over 25 h with almost no change in the cell voltage. The superior catalytic activity and stability at large current densities (>500 mA cm⁻²) far exceed the benchmark RuO₂ and Pt/C catalysts. This work sheds a new light on the development of highly active and stable nonprecious electrocatalysts for industrial water electrolysis.     

Flower-like HEA/MoS2/MoP heterostructure based on interface engineering for efficient overall water splitting

The development of cheap, efficient, and active non-noble metal electrocatalysts for total hydrolysis of water (oxygen evolution reaction (OER) and hydrogen evolution reaction (HER)) is of great significance to promote the application of water splitting. Herein, a heterogeneous structured electrode based on FeAlCrMoV high-entropy alloy (HEA) was synthesized as a cost-effective electrocatalyst for hydrogen and oxygen evolution reactions in alkaline media. In combination of the interfacial synergistic effect and the high-entropy coordination environment, flower-like HEA/MoS₂/MoP exhibited the excellent HER and OER electrocatalytic performance. It showed a low overpotential of 230 mV at the current density of 10 mA cm⁻² for OER and 148 mV for HER in alkaline electrolyte, respectively. Furthermore, HEA/MoS₂/MoP as both anode and cathode also exhibited an overpotential of 1.60 V for overall water splitting. This work provides a new strategy for heterogeneous structure construction and overall water splitting based on high-entropy alloys.     

Engineering FeNi-based electrocatalysts conjoined with Mo2C grown on carbon spheres toward efficient water oxidation via structure and electronic modulation

The development of active non-noble electrocatalysts for oxygen evolution reaction (OER) is urgently desired to accomplish high-performance electrocatalytic water splitting. Here, we report a unique structure electrocatalyst composed of FeNi and Mo₂C heterojunction as spherical shell supported on carbon sphere as core for efficient OER. With the aid of Mo₂C incorporation, FeNi–Mo₂C@C shows increased specific surface area, more electrocatalytic active sites, improved surface water adsorption, and reduced energy barrier. Benefiting from the synergy of shell-core and heterojunction sturcture, the optimized FeNi–Mo₂C@C exhibits superior activity for OER with an overpotential of 283 mV at 10 mA cm⁻² as well as Tafel slope of 29.2 mV dec⁻¹, which is comparable to that of the benchmark ruthenium oxide. The feasible bond between structural design and electronic alteration enhances the charge transfer efficiency, conductivity, and catalytic kinetics, thus intrinsically boost the electrocatalytic performance. This study hence supports a viable strategy to develop highly-efficient non-precious OER electrocatalysts through structural and electronic modification.     

Cobalt carbonate hydroxide assisted formation of self-supported CoNi-based Metal–Organic framework nanostrips as efficient electrocatalysts for oxygen evolution reaction

The development of efficient and low-cost electrocatalysts is crucial for improving the efficiency of electrochemical oxygen evolution reaction (OER). Herein, self-supported CoNi-based metal-organic framework (MOF) nanostrips grown on Ni foam (NF) were synthesized with cobalt carbonate hydroxide (CoCH) nanoneedles as a sacrificial template and demonstrated to be highly efficient electrocatalysts for OER. In this approach, the CoCH nanoneedles play a key role in modulating the morphology of CoNi-MOF with reduced thickness and sizes through affording Co source and slowing down the leaching of Ni ions from the NF substrate. The resultant CoNi-MOF/CoCH/NF electrode possesses higher catalytically active surface area and smaller electrochemical impedance than CoCH template-free electrodes, which enable rapid mass transport and charge transfer during OER, thus showing enhanced electrocatalytic activity for OER. In alkaline media (1.0 M KOH), it needs a low overpotential of 251 mV to deliver a current density of 10 mA cm⁻² and exhibits a small Tafel slope of 40.7 mV dec⁻¹ as well as excellent durability. The developed approach may inspire further capability on constructing more promising catalysts for energy related applications.     

Heterostructural Co/CeO2/Co2P/CoP@NC dodecahedrons derived from CeO2-inserted zeolitic imidazolate framework-67 as efficient bifunctional electrocatalysts for overall water splitting

The design and fabrication of highly active, robust and cost-efficient electrocatalysts for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is of great significance towards overall water splitting, but remains challenging as well. Herein, we report, for the first time, heterostructural Co/CeO₂/Co₂P/CoP@NC dodecahedrons as bifunctional electrocatalyst, in which abundant interfaces are formed between different components. Typical ZIF-67 (ZIF = zeolitic imidazolate framework) dodecahedrons with pre-inserted CeO₂ nanowires were selected as precursors to synthesize Co/CeO₂/Co₂P/CoP@NC via a direct carbonization process followed by phosphidation, simultaneously generating the strong coupled heterojunction interfaces through interactions between CeO₂ and Co_xP species. Abundant porous structure leads to the exposure of more active sites and the carbon encapsulation of nanodomains sustains the high robustness and conductivity and the synergistic effect between the multi-components heterostructure. Benefiting from the above collective advantages, the Co/CeO₂/Co₂P/CoP@NC electrocatalysts exhibit small overpotentials of 307 and 195 mV to derive 10 mA cm⁻² for OER and HER, respectively. Furthermore, an alkaline electrolyzer assembled by using Co/CeO₂/Co₂P/CoP@NC as both cathode and anode can achieve a current density of 10 mA cm⁻² at a low voltage of 1.76 V and work continuously for over 15 h. This work would provide a rational protocol for fabrication multi-phase interface enriched electrocatalysts toward highly efficient energy conversion.     

Construction of two-dimensional CoPS3@defective N-doped carbon composites for enhanced oxygen evolution reaction

The rational design of highly efficient, economical and environment-friendly electrocatalysts is currently an important goal of research on renewable energy conversion and storage. Herein, a facile metod was developed to construct two-dimensional composites, which consist of exfoliated CoPS₃ nanosheets grafted onto defective N-doped carbon (DNC) derived from spent tea leaves. The CoPS₃@DNC composites demonstrate remarkable oxygen evolution reaction (OER) performance in an alkaline medium, with an overpotential of 297 mV at 10 mA cm^{? 2} and a small Tafel slope of 51.8 mV dec^?1, which is better than that of commercial IrO₂ catalysts. Our experimental evidence reveals that the enhanced OER performance of this hybrid catalyst can be attributed to the interfacial effect of exfoliated CoPS₃ and N-doped carbon defects (electron transfer from the CoPS₃ layer to DNC). This work suggests a promising interface engineering technique for developing highly efficient and non-precious OER catalysts based on layered transition-metal trichalcogenides.