Commercial RuO2 Research Articles

Effects of Capping Agents on Shape, Stability, and Oxygen Evolution Reaction Activity of Copper Nanoparticles

Here, five different capping agents’ polyethylene glycol (PEG), cetyltrimethylammonium bromide (CTAB), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and oleylamine (OAm) are used to form copper nanoparticles (Cu-NPs), along with their electrocatalytic oxygen evolution reaction (OER) properties. The produced Cu-NPs’ mono-dispersity and their interactions with PEG, CTAB, PVA, PVP, and OAm were examined. The mean particle size determined by TEM images for the uncapped Cu-NPs as generated, PVA-capped, PVP-capped, CTAB-capped, PEG-capped, and OAm-capped samples, respectively, were 2.71 nm, 2.22 nm, 3.10 nm, 3.31 nm, 1.49 nm, and 1.71 nm. Greater than prepared catalysts, commercial Pt/C has a 3.7 nm size. It’s interesting to note that the CTAB-capped Cu-NPs considerably exhibit the strongest OER activity, with a very low overpotential of 222 mV at 10 mA cm−2, lower than many previously reported and the high electrocatalytic activity for OER of the commercial RuO2 catalysts. However, an expedited stress experiment shows that the CTAB-capped NPs have greater structural stability during electrochemical cycling. Their strong capping tendency and particle shape are the key causes of this. The approach for creating Cu nanocatalysts described in this paper has several potential uses for the creation of bimetallic catalysts.

Construction of 3D Hierarchical Co3O4@CoFe-LDH Heterostructures with Effective Interfacial Charge Redistribution for Rechargeable Liquid/Solid Zn-Air Batteries.

Constructing three-dimensional (3D) hierarchical heterostructures is an appealing but challenging strategy to improve the performance of catalysts for electrical energy devices. Here, an efficient and robust flexible self-supporting catalyst, interface coupling of ultrathin CoFe-LDH nanosheets and Co3O4 nanowire arrays on the carbon cloth (CC/Co3O4@CoFe-LDH), was proposed for boosting oxygen evolution reaction (OER) in rechargeable liquid/solid Zn-air batteries (ZABs). The strong interfacial interaction between the CoFe-LDH and Co3O4 heterostructures stimulated the charge redistribution in their coupling regions, which improved the electron conductivity and optimized the adsorption free energy of OER intermediates, ultimately boosting the intrinsic OER performance. Besides, the 3D hierarchical nanoarray structure facilitated the exposure of catalytically active centers and rapid electron/mass transfer during the OER process. As such, the CC/Co3O4@CoFe-LDH catalyst achieved excellent OER catalytic activity in alkaline medium, with a small overpotential of 237 mV at 10 mA cm-2, a low Tafel slope of 35.43 mV dec-1, and long-term durability of up to 48 h, significantly outperforming the commercial RuO2 catalyst. More impressively, the liquid and flexible solid-state ZABs assembled by the CC/Co3O4@CoFe-LDH hybrid catalyst as the OER catalyst presented a stable open circuit voltage, large power density, superb cycling life, and satisfactory flexibility, indicating great potential applications in energy technology. This work provides a good guidance for the development of advanced electrocatalysts with heterostructures and an in-depth understanding of electronic modulation at the heterogeneous interface.

In Situ Porousized MoS2 Nano Islands Enhance HER/OER Bifunctional Electrocatalysis.

2D molybdenum disulfide (MoS2 ) is developed as a potential alternative non-precious metal electrocatalyst for energy conversion. It is well known that 2D MoS2 has three main phases 2H, 1T, and 1T'. However, the most stable 2H-phase shows poor electrocatalysis in its basal plane, compared with its edge sites. In this work, a facile one-step hydrothermal-driven in situ porousizing of MoS2 into self-supporting nano islands to maximally expose the edges of MoS2 grains for efficient utilization of the active stable sites at the edges of MoS2 is reported. The results show that such active, aggregation-free nano islands greatly enhance MoS2 's hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) bifunctional electrocatalytic activities. At a low overpotential of 248 and 300 mV, the porous MoS2 nano islands can generate a current density of 10 mA cm-2 in HER and OER, which is much better than typical nanosheet morphology. Surprisingly, the porous MoS2 nano islands even exhibit better performance than the current commercial RuO2 catalyst in OER. This discovery will be another effective strategy to promote robust 2H-phase, instead of 1T/1T'-phase, MoS2 to achieve efficient endurable bifunctional HER/OER, which is expected to further replace precious metal catalysts in industry.

Dual Integrating Oxygen and Sulphur on Surface of CoTe Nanorods Triggers Enhanced Oxygen Evolution Reaction.

The bottleneck of large-scale implementation of electrocatalytic water-splitting technology lies in lacking inexpensive, efficient, and durable catalysts to accelerate the sluggish oxygen evolution reaction kinetics. Owing to more metallic features, transition metal telluride (TMT) with good electronic conductivity holds promising potential as an ideal type of electrocatalysts for oxygen evolution reaction (OER), whereas most TMTs reported up to now still show unsatisfactory OER performance that is far below corresponding sulfide and selenide counterparts. Here, the activation and stabilization of cobalt telluride (CoTe) nanoarrays toward OER through dual integration of sulfur (S) doping and surface oxidization is reported. The as-synthesized CoO@S-CoTe catalyst exhibits a low overpotential of only 246mV at 10mAcm-2 and a long-term stability of more than 36h, outperforming commercial RuO2 and other reported telluride-based OER catalysts. The combined experimental and theoretical results reveal that the enhanced OER performance stems from increased active sites exposure, improved charge transfer ability, and optimized electronic state. This work will provide a valuable guidance to release the catalytic potential of telluride-based OER catalysts via interface modulating engineering.

Dumbbell Defect Containing Chromium-Rich Lithium-Vacant Layered LiyCr1–xFexO2(y≤ 1, 0 ≤x≤ 0.2): An Unexplored and Highly Efficient Electrocatalyst for the Oxygen Evolution Reaction

Oxygen electrochemistry plays a critical role in water electrolysis, fuel cells, and metal–air batteries as efficient energy storage and conversion technology to harness renewable energies. Dumbbell defects containing chromium-rich lithium-vacant layered structure LiCrO2 are envisaged here as an efficient oxygen evolution reaction (OER) electrocatalyst due to the presence of Cr6+ ions at interstitial sites that facilitates −Cr–O–OH formation in basic media. The presence of Cr6+ ions at the dumbbell interstitial sites of the hexagonal close-packed LiCrO2 lattice was confirmed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy studies. The crystal structure, morphology, and composition of the materials were confirmed by powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and inductively coupled plasma–mass spectrometry analysis. Rhombohedral structure formation and formation of Cr6+ ion interstitials in the Li layer increase that varies with Fe doping in LiyCr1–xFexO2 (y ≤ 1, 0 ≤ x ≤ 0.2), and the best OER activity is achieved for Li0.6Cr0.9Fe0.1O2 (LCFO-10) with a Tafel slope of 50 mV dec–1 and an overpotential of 311 mV at a current density of 10 mA cm–2, better than that of the RuO2 (overpotential ∼336 mV) benchmark catalyst. At an overpotential of 350 mV, the OER current density of LCFO-10 is 28.07 mA cm–2, which is ∼2 times higher than the OER current density observed with commercial RuO2 (13.22 mA cm–2), indicating its superior electrocatalytic performances. The remarkable enhancement of OER performance may be attributed to the synergistic interaction of Cr6+ and Fe3+ ions present in the lattice.

One-step achievement of Fe-doped and interfacial Ru nanoclusters co-engineered Ni(OH)2 electrocatalyst on Ni foam for promoted oxygen evolution reaction

The creation of inexpensive, high-performance catalysts to reduce the overpotential of the oxygen evolution reaction (OER) process is critical for the electrolysis of water for hydrogen production. Therefore, we applied a one-step hydrothermal method using cation exchange reaction (CER) to prepare Fe-doped and interfacial Ru nanoclusters co-engineered Ni(OH)2 nanosheets directly grafted on Ni foam (Ru@Fe-Ni(OH)2/NF) for OER process. Results of electrochemical tests reveal that Ru@Fe-Ni(OH)2/NF has excellent OER activity, and its overpotential (η) is only 266.4 mV when the current density is 50 mA cm−2 in 1 M KOH solution, even lower than that of commercial OER catalyst RuO2 (355 mV). The Tafel slope also decreases from 133.8 mV dec−1 for pristine Ni(OH)2/NF material to 24.1 mV dec−1 for Ru@Fe-Ni(OH)2/NF, indicating the higher charge transfer rates and fastest kinetics for water oxidation. At an overpotential of 300 mV the optimal turnover frequency (TOF) of 0.062 s−1 for Ru@Fe-Ni(OH)2/NF is achieved compared to that of Ni(OH)2/NF (0.014 s−1, NN), demonstrating the fast reaction kinetics of the as-prepared electrocatcalyst. After 24 h stability test, the catalytic activity of Ru@Fe-Ni(OH)2/NF was only attenuated by 2 %, showing excellent OER stability and durability. Our results show that we have successfully developed an efficient OER catalyst for green and efficient electrocatalytic hydrolysis to produce H2 and O2, providing a promising method for clean H2 production.

Ultrafast synthesis of cobalt/carbon nanocomposites by magnetic induction heating for oxygen evolution reaction

Metal/carbon nanocomposites have shown great potential as high-performance, low-cost electrocatalysts owing largely to their unique metal-support interactions. These nanocomposites are typically prepared by conventional pyrolysis that is tedious and energy-intensive. Herein, we report the ultrafast preparation of cobalt/carbon nanocomposites by magnetic induction heating (MIH) of metal organic frameworks within seconds under an inert atmosphere. The resulting samples consist of cobalt nanoparticles encapsulated within defective carbon shells, and effectively catalyze oxygen evolution reaction (OER) in alkaline media. Among the series, the sample prepared at 400 A for 10 s exhibits the best OER performance, needing a low overpotential of +308 mV to reach the current density of 10 mA cm−2, along with excellent stability, and even outperforms commercial RuO2 at high overpotentials. This is ascribed to the charge transfer between the carbon scaffold and metal nanoparticles. Operando X-ray absorption spectroscopy measurements show that the electrochemically produced CoOOH species is responsible for the high electrocatalytic performance. The results highlight the unique potential of MIH in the development of effective nanocomposite catalysts for electrochemical energy technologies.

SnO2/CoS1.097 heterojunction as a green electrocatalyst for hydrogen evolution linking to assistant glycerol oxidation

Different ratios of Sn and Co sources were designed and mixed to obtain SnO2/CoS1.097 heterojunctions. As a potential electrocatalyst, the 0.5SnO2/0.5CoS1.097 is superior to the commercial RuO2 and Pt/C electrocatalysts.

Highly dispersed Pt with CoFeP hollow nanocages for efficient oxygen evolution reaction

The strong binding energy of Pt with oxygen intermediates results in its low OER efficiency at the anode. Herein, Pt-doped CoFeP (Pt-CoFeP) material has been synthesized using CoFe-PBA as precursor through facile etching and phosphating processes. Interestingly, Pt-CoFeP with hollow cage framework exhibits large surface area after etching, which plays a domain-limiting role for the high dispersion of platinum atoms and facilitates the oxygen evolution reaction (OER). The target sample Pt-CoFeP only needs low overpotentials of 311.7 and 343.1 mV to deliver the current density of 10 and 50 mA cm-2, which is superior to commercial RuO2. The excellent activity can be attributed to large specific surface area in hollow framework and highly dispersed platinum atoms. And its great durability is evaluated through chronoamperometry measurement for 12 hours. This work provides a potential method to design electrocatalysts with complex structure loaded with highly dispersed Pt particles derived from Prussian blue analogues (PBAs) for water splitting.

Densely populated tiny RuO2 crystallites supported by hierarchically porous carbon for full acidic water splitting.

The exploitation of highly active bifunctional electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acidic media has been a subject receiving immense interest. However, the existing catalysts usually suffer from low catalytic efficiency and poor corrosion resistance under acidic conditions. Herein, we report a facile molten salt method to fabricate ruthenium dioxide nanoparticles supported by hierarchically porous carbon (RuO2/PC) as a bifunctional electrocatalyst for full water splitting under strong acidic conditions. The formation of a densely populated nanocrystalline RuO2/carbon heterostructure helps expose catalytic sites, accelerates the mass transfer rate, and further enhances the acid resistance of RuO2 nanoparticles. The as-synthesized RuO2/PC consequently exhibits superior catalytic performance for the OER with an overpotential of 181 mV upon 10 mA cm-2 compared to that of the commercial RuO2 (343 mV) and a comparable performance to Pt/C for the HER (47.5 mV upon 10 mA cm-2) in 0.5 M H2SO4. The RuO2/PC shows promising stability with little degradation over ∼24 h. Impressively, the water electrolyzer based on RuO2/PC shows an overpotential of 326 mV at 10 mA cm-2, much lower than that of the electrolyzer based on the combination of Pt/C and RuO2 (400 mV), indicating its great potential towards practical application.

Interface engineering of NiTe/NiCo-LDH core-shell structure to enhance oxygen evolution electrocatalysis performance

Non-noble metal-based heterostructures have emerged as a promising strategy to construct high-efficient electrocatalysts for the Oxygen evolution reaction. Herein, we reported a three-dimensional core-shell heterostructures of NiTe/NiCo-LDH (NiCo layered double hydroxides) on the Ni foam to resolve the low electronic conductivity and self-aggregation of NiCo-LDH. This NiTe/NiCo-LDH electrocatalyst could be prepared from a two-step reaction as a hydrothermal reaction and electrodeposition approach. Benefiting from the existence of strong interface effects between the NiTe nanorod core and NiCo-LDH nanosheet shell, the NiTe/NiCo-LDH electrocatalyst exhibited superior activity for the Oxygen evolution reaction at a current density of 100 mA cm−2 with an overpotential of 376 mV in 1.0 M KOH solution, which was significantly smaller than that of a single component of NiTe (586 mV), NiCo-LDH (410 mV) and commercial RuO2 (428 mV). Furthermore, the NiTe/NiCo-LDH catalyst indicated long-term stability after 24 h continuous working. Density functional theory computations unveil that the heterostructures modified the original electronic structures and weakened the atomic interaction in the LDH layers, which have effectively adjusted the d-band center of the catalytic active Co sites to the Fermi level. This work demonstrated an effective strategy of interfacial engineering to optimize electron transfer to boost Oxygen evolution reaction performance.

Hierarchical heterostructure of NiFe2O4 nanoflakes grown on the tip of NiCo2O4 nanoneedles with enhanced interfacial polarization effect to achieve highly efficient electrocatalytic oxygen evolution

In this work, a heterostructure oxygen evolution reaction (OER) electrocatalyst consisting of NiFe2O4 nanoflakes grown on the tip of NiCo2O4 nanoneedles arrays supported on nickel foam (NCO-NNs@NFO-NFs/NF) was obtained via simultaneous cation (Co3+ by Fe3+) and ligand exchange (-OH by 1,4-benzenedicarboxylic acid) and further annealing of the hydroxide/MOF precursor in air. HRTEM and Raman characterizations confirm the formation of NCO/NFO heterostructure. XPS characterization and charge density difference calculations clarify the electron transfer from Fe to Ni and Co at the NCO/NFO heterointerface. Electrochemical tests show that NCO-NNs@NFO-NFs/NF possesses excellent OER electrocatalytic activity (overpotential of 265 mV@50 mA cm−2) and durability (stable for 100 h@1 A cm−2). NCO-NNs@NFO-NFs/NF‖20 % Pt/C two-electrode system can achieve 10 mA cm−2 at 1.398 V for anion exchange membrane (AEM) water splitting in 1.0 M KOH at 85 °C, which exceeds the activity of using commercial RuO2 as an anode at 25 °C, combined with the stability of 100 h at 10 mA cm−2 at 25 °C, demonstrating the practical application in industrial AEM process. XPS and HRTEM characterizations of NCO-NNs@NFO-NFs/NF after the OER V-t test, along with ex-situ Raman characterization, confirm that Co and Fe sites undergo surface reconstruction to form specific CoOOH/FeOOH interfaces, as to exert the synergistic effect of Co and Fe dual active sites during OER process. DOS calculations reveal that the density of state at Fermi energy level increases after the introduction of Fe, thereby improving conductivity and facilitating the activation of adsorbed oxygen species. This study shows a significant methodology for simultaneous improvement of the electrocatalytic stability and activity of spinel oxides-based heterostructures, which is critical for practical application.

Proton production in neutral electrolyte along oxygen evolution

Proton production is imperative for many electrochemical reduction reactions, and the ability of an electrocatalyst to facilitate its production is vital for electrocatalysis. Herein commercial RuO2 is employed as our electrocatalyst for proton generation during oxygen evolution in a neutral electrolyte (0.2 M Na2SO4). The RuO2 catalyst achieves a low Tafel slope of 93 mV/dec and an overpotential of 570 mV at a current density of 10 mA cm−2. Its mass activity is calculated to be 12.37 A g−1. The Faradaic efficiency of proton generation (FEH+) is found to be 96.8%, 96.3%, 92.5%, 91.3%, and 90.8% at 1.8 V vs. RHE after 1, 3, 6, 9, and 12 h of electrolysis, respectively with a proton yield of 23.75%, 16.41%, 17.10%, 16.78%, and 20.89%, respectively. This study on facilitating proton production will greatly enhance efficiency across myriad energy conversion reactions. The acidified electrolyte can be reused in other applications.

Activating catalytic behavior of binary transition metal sulfide-shelled carbon nanotubes by iridium incorporation toward efficient overall water splitting

To meet the future demand for green energy, the development of catalysts for water splitting has become an essential task for scientists worldwide. In this context, a novel catalyst that relies on Ir-doped CoNi2S4 nanosheets assembled on carbon nanotubes, supported on three-dimensional carbon framework has been developed. The outstanding advantages of core-shell heterostructure and heteroatom doping are that they induce high abundance of exposed active sites and excellent ability for mass/charge transport of the catalyst. Thus, the catalyst provides excellent activity for hydrogen evolution reaction, which surpasses that of the noble-metal-free electrocatalysts reported in the literature. The catalyst also shows superior catalytic behavior for oxygen evolution reaction, which is even better than that of the commercial RuO2 catalyst. Impressively, the electrolyzer using the proposed catalyst requires small cell voltages of only 1.60 V and 1.94 V at response current density of 10 mA/cm2 and 50 mA/cm2, respectively. More importantly, this electrolyzer manifests much better stability and durability than those of the electrolyzer using commercial Pt/C and RuO2 catalysts.

Direct Visualization of Atomic Structure in Multivariate Metal-Organic Frameworks (MOFs) for Guiding Electrocatalysts Design.

The direct utilization of metal-organic frameworks (MOFs) for electrocatalytic oxygen evolution reaction (OER) has attracted increasing interests. Herein, we employ the low-dose integrated differential phase contrast-scanning transmission electron microscopy (iDPC-STEM) technique to visualize the atomic structure of multivariate MOFs (MTV-MOFs) for guiding the structural design of bulk MOFs for efficient OER. The iDPC-STEM images revealed that incorporating Fe3+ or 2-aminoterephthalate (ATA) into Ni-BDC (BDC: benzenedicarboxylate) can introduce inhomogeneous lattice strain that weaken the coordination bonds, which can be selectively cleaved via a mild heat treatment to simultaneously generate coordinatively unsaturated metal sites, conductive Ni@C and hierarchical porous structure. Thus, excellent OER activity with current densities of 10 and 100 mA cm-2 are achieved over the defective MOFs at small overpotentials of 286 mV and 365 mV, respectively, which is superior to the commercial RuO2 catalyst and most of the bulk MOFs.

Direct Visualization of Atomic Structure in Multivariate Metal‐Organic Frameworks (MOFs) for Guiding Electrocatalysts Design

AbstractThe direct utilization of metal–organic frameworks (MOFs) for electrocatalytic oxygen evolution reaction (OER) has attracted increasing interests. Herein, we employ the low‐dose integrated differential phase contrast‐scanning transmission electron microscopy (iDPC‐STEM) technique to visualize the atomic structure of multivariate MOFs (MTV‐MOFs) for guiding the structural design of bulk MOFs for efficient OER. The iDPC‐STEM images revealed that incorporating Fe3+ or 2‐aminoterephthalate (ATA) into Ni‐BDC (BDC: benzenedicarboxylate) can introduce inhomogeneous lattice strain that weaken the coordination bonds, which can be selectively cleaved via a mild heat treatment to simultaneously generate coordinatively unsaturated metal sites, conductive Ni@C and hierarchical porous structure. Thus, excellent OER activity with current densities of 10 and 100 mA cm−2 are achieved over the defective MOFs at small overpotentials of 286 mV and 365 mV, respectively, which is superior to the commercial RuO2 catalyst and most of the bulk MOFs.

Constructing nickel vanadium phosphide nanoarrays with highly active heterointerfaces for water oxidation in alkali media

Developing low-cost, ultra-stable, and active non-noble metal catalyst is distinctly indispensable for oxygen evolution reaction (OER). Herein, an ordered nickel vanadium phosphide (NiVP) nanoarray catalyst with abundant interfaces was successfully constructed via a facile multi-step strategy. Notably, the interface-rich NiVP nanoarray shows excellent activity for OER in the alkaline solution, which just requires a low overpotential of 253 mV at current density of 10 mA cm−2 and displays a Tafel slope of 78 mV dec−1, obviously outperforms commercial RuO2. Further studies confirmed that the heterojunction interface between nickel phosphide (Ni2P) and nickel oxyhydroxide acts as the main role for OER, which could optimize the adsorption of oxygen intermediates due to the electron migration. Moreover, heterointerfaces are also beneficial to the exposure of active sites during OER, effectively accelerating the reaction kinetics. This work develops a novel electrocatalyst with superior activity for OER, contributing to the development of water splitting driven by renewable energy.

Ru/Se‐RuO2 Composites via Controlled Selenization Strategy for Enhanced Acidic Oxygen Evolution

AbstractThe introduction of electronegative non‐metallic heterostructures is promisingly desired to develop Ru‐based oxide catalysts, which have higher activity and robust stability for acidic oxygen evolution reaction (OER). Developing scalable synthetic strategies and enlightening the mechanism understanding of the enhancement is imperative but still challenging. Herein, a facile selenium‐assisted reduction approach is reported to fabricate the partially reduced nano‐sized Ru with mixed‐valence Se species immobilization, directly from commercial RuO2 through ball milling and annealing procedures. The obtained Ru/Se‐RuO2 composites demonstrate superior electrocatalytic performance toward acidic OER with small overpotentials of 190 and 240 mV at 10 and 100 mA cm−2, a Tafel slope of only 43.7 mV dec−1, and no detectable activity decay under operation for 24 h. Experimental results further demonstrate a synergistic effect including enhanced electron transfer interaction by the formation of Ru/RuO2 heterostructures and more available active sites due to Se doping. Theoretical calculations indicate that slight Se doping and metallic Ru loading can significantly decrease the free energy change for the formation of *OOH intermediate, and thus dramatically promotes the OER performance. This strategy offers a promising strategy for the development of non‐metallic elements incorporated high‐performance catalysts and related water electrocatalytic devices for sustainable energy applications.

Construction of Co(CO3)0.5OH/Cu Mott-Schottky heterojunctions on Ni foams as an efficient electrocatalyst for oxygen evolution reaction

Oxygen evolution reaction (OER) is an important semi-reaction in the electrolysis of water, but it requires a cheap and efficient catalyst to solve the inherent problem of slow kinetics. In this work, we present an efficient strategy to improve electrocatalytic performance by constructing a Mott-Schottky heterojunction via the Cu layer. The Co(CO3)0.5OH/Cu/NFs sample with a Mott-Schottky structure was prepared by depositing Co(CO3)0.5OH nanowire arrays on the surface of NFs plated with a Cu layer. The sample can deliver much better OER performance given the low overpotential of 253 mV at 10 mA cm−2, and extremely low Tafel slope of 48 mV dec−1, even lower than that of commercial OER catalyst RuO2. The significant performance enhancement can be attributed to the Mott-Schottky structure of Co(CO3)0.5OH/Cu. In particular, the intrinsic activity of the sample is improved by the Mott-Schottky structure of Co(CO3)0.5OH/Cu, in which the spontaneous electron will transfer from Cu to Co(CO3)0.5OH, hence reducing the OER overpotential. Then, the conductivity of the sample is initially enhanced by the Cu layer, thus improving the charge transport speed in the process of OER. Furthermore, in the constructed sandwich structure, the dense Co(CO3)0.5OH and NF substrates can avoid the corrosion of Cu by the electrolyte, maintaining good stability beyond 50 h. This strategy is also applicable to other OER materials, such as NiFe LDH, CuNi LDH, and CoP, and their performances can be significantly improved. This work provides a universal method of constructing efficient Mott-Schottky electrocatalysts for OER, consequently providing a wide range of application prospects.

Coupling the vanadium-induced amorphous/crystalline NiFe2O4 with phosphide heterojunction toward active oxygen evolution reaction catalysts

Abstract Developing efficient and robust electrocatalysts is increasingly essential for water splitting, severely hindered by the sluggish four-electron transfer process of oxygen evolution reaction (OER). Amorphous/crystalline heterophase engineering has recently emerged as a promising electronic modulation approach for OER catalysts but suffers from poor conductivity of the amorphous structure. Here, we coupled the amorphous/crystalline NiFe2O4 induced by vanadium doping with NiP heterojunction, highlighting the synergistic effect in modulating the electronic structures and the complementary effect in promoting conductivity. As a superior electrocatalyst to commercial RuO2, the as-prepared NFO-V0.3-P showed a low overpotential of 277 mV at the current density of 20 mA cm−2, a Tafel slope of 45 mV dec−1, and long-term stability. The excellent OER catalytic activity is attributed to the synergistic effect at the heterophase interface with rich active sites, fine-tuning of electronic regulation, and enhanced conductivity.