Effective Oxygen Evolution Reaction Electrocatalysts Research Articles

Ultrathin high-entropy layered double hydroxide electrocatalysts for enhancing oxygen evolution reaction

At the heart of the oxygen evolution reaction (OER), the properties of electrocatalysts play a crucial role in determining reaction efficiency. This underscores the need to design and develop highly effective OER electrocatalysts. The unique layer structure and electronic properties make layer double hydroxide (LDH) a promising candidate for driving OER electrocatalysis. Furthermore, high-entropy materials (HEMs) exhibit core effects such as high entropy, lattice distortion, sluggish diffusion, and cocktail effect, which can enhance active sites and optimize binding energy with intermediates. Combining the advantages of these two material categories, we propose the synthesis of high-entropy layered double hydroxides (HE-LDHs) through a straightforward MOF-mediated synthesis method to showcase exceptional electrocatalytic OER performance. Detailed mechanistic studies have shown that its outstanding performance stems from its ultrathin structure and the inherent activity of a high-entropy material that promotes charge transfer, mass transport, and the evolution of reaction intermediates.

Hydrothermally synthesized rGO based FeSe nanocomposite as electrocatalyst for oxygen evolution reaction

Highly productive catalysts are necessary in oxygen evolution reaction (OER) to lower overpotential and enhance sluggish kinetics of the reaction. In this work, we present an effective OER electrocatalyst, i.e. composite of FeSe with reduced graphene oxide (FeSe/rGO) fabricated via hydrothermal method. Its main challenges include low electron conductivity and inadequate active site exposure. Meanwhile, the reduced graphene oxide (rGO) composite improves the conductivity, which raises OER activity and provides large electrochemical surface area. Different physical techniques were used to analyze the composite, according to BET surface area of FeSe/rGO was (201 cm3 g−1). To assess electrochemical characteristics of composite electrochemical impedance spectroscopy (EIS) cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry was utilized. In comparison to benchmark of commercial RuO2, the FeSe/rGO catalyst exhibits a reduced overpotential (194 mV) and minimal Tafel slope (31 mV dec−1). FeSe/rGO exhibits exceptional stability and long-term durability to be used for OER. This work not only show low overpotential value of FeSe/rGO nanocomposite, but it also introduces a novel method for producing composite materials that are inexpensive and perform well and can be utilized in different future applications.

A stable N-doped NiMoO4/NiO2 electrocatalyst for efficient oxygen evolution reaction.

Recently, there has been a significant interest in the study of highly active and stable transition metal-based electrocatalysts for the oxygen evolution reaction (OER). Non-noble metal nanocatalysts with excellent inherent activity, many exposed active centers, rapid electron transfer, and excellent structural stability are especially promising for the displacement of precious-metal catalysts for the production of sustainable and "clean" hydrogen gas through water-splitting. Herein, efficient electrocatalyst N-doped nickel molybdate nanorods were synthesized on Ni foam by a hydrothermal process and effortless chemical vapor deposition. The heterostructure interface of N-NiMoO4/NiO2 led to strong electronic interactions, which were beneficial for enhancing the OER activity of the catalyst. Excellent OER catalytic activity in 1.0 M KOH was shown, which offered a small overpotential of 185.6 mV to acquire a current density of 10 mA cm-2 (superior to the commercial benchmark material RuO2 under the same condition). This excellent electrocatalyst was stable for 90 h at a constant current density of 10 mA cm-2. We created an extremely reliable and effective OER electrocatalyst without the use of noble metals by doping a nonmetal element with nanostructured heterojunctions of various active components.

In Situ Electrochemical Restructuring B-Doped Metal-Organic Frameworks as Efficient OER Electrocatalysts for Stable Anion Exchange Membrane Water Electrolysis.

Metal organic frameworks (MOFs) are promising as effective electrocatalysts toward oxygen evolution reaction (OER). However, the origin of OER activity for MOF-based electrocatalysts is still unclear because of their structure reconstruction during electrocatalysis process. Here, a novel MOF (B-MOF-Zn-Co) with spherical superstructure is developed by hydrothermal treatment of zeolitic imidazolate framework-Zn, Co (ZIF-Zn-Co) using boric acid. The resultant B-MOF-Zn-Co shows high OER activity with a low overpotential of 362mV at 100mA cm-2. Remarkably, B-MOF-Zn-Co displays excellent stability with only 3.6% voltage delay over 300h at 100mA cm-2 in alkaline electrolyte. Surprisingly, B-MOF-Zn-Co thoroughly transforms into B-doped CoOOH (B-CoOOH) during electrolysis process, which isserved as actual active material for high OER electrocatalytic performance. The newly-formed B-CoOOH possesses lower energy barrier of potential-determining step (PDS) for OOH* formation compared with CoOOH, benefiting for high OER activity. More importantly, B-MOF-Zn-Co based anion exchange membrane water electrolytic cell (AEMWE) demonstrates continuously durable operation with stable current density of 200mA cm-2 over 300h, illustrating its potential application in practice water electrolysis. This work offers an in situ electrochemical reconstruction strategy for the development of stable and effective OER electrocatalysts toward practice AEMWE.

Modulation of Electronic Synergy to Enhance the Intrinsic Activity of Fe5Ni4S8 Nanosheets in Restricted Space Carbonized Wood Frameworks for Efficient Oxygen Evolution Reaction.

Modulation of electronic structure and composition is widely recognized as an effective strategy to improve electrocatalyst performance. Herein, using a simple simultaneous carbonization and sulfidation strategy, NiFe double hydroxide-derived Fe5Ni4S8 (FNS) nanosheets immobilized on S-doped carbonized wood (SCW) framework by taking benefit of the orientation-constrained cavity and hierarchical porous structure of wood is proposed. Benefiting from the synergistic relationships between bimetal ions, the spatial confinement offered by the wood cavity, and the enhanced structural effects of the nanosheets array, the FNS/SCW exhibit enhanced intrinsic activity, increased accessibility of catalytically active sites, and convection-facilitated mass transport, resulting in an excellent oxygen evolution reaction (OER) activity and durability. Specifically, it takes a low overpotential of 230mV at 50mAcm-2 and potential increase is negligible (3.8%) at 50mAcm-2 for 80hours. Density functional theory (DFT) calculations further reveal that the synergistic effect of bimetal can optimize the electronic structure and lower the reaction energy barrier. The FNS/SCW used as the cathode of zinc-air battery shows higher power density and excellent durability relative to commercial RuO2, exhibiting a good application prospect. Overall, this research offers proposals for designing and producing effective OER electrocatalysts using sustainable resources.

Nanoengineered, Pd-doped Co@C nanoparticles as an effective electrocatalyst for OER in alkaline seawater electrolysis

Water electrolysis is considered one of the major sources of green hydrogen as the fuel of the future. However, due to limited freshwater resources, more interest has been geared toward seawater electrolysis for hydrogen production. The development of effective and selective electrocatalysts from earth-abundant elements for oxygen evolution reaction (OER) as the bottleneck for seawater electrolysis is highly desirable. This work introduces novel Pd-doped Co nanoparticles encapsulated in graphite carbon shell electrode (Pd-doped CoNPs@C shell) as a highly active OER electrocatalyst towards alkaline seawater oxidation, which outperforms the state-of-the-art catalyst, RuO2. Significantly, Pd-doped CoNPs@C shell electrode exhibiting low OER overpotential of ≈213, ≈372, and ≈ 429 mV at 10, 50, and 100 mA/cm2, respectively together with a small Tafel slope of ≈ 120 mV/dec than pure Co@C and Pd@C electrode in alkaline seawater media. The high catalytic activity at the aforementioned current density reveals decent selectivity, thus obviating the evolution of chloride reaction (CER), i.e., ∼490 mV, as competitive to the OER. Results indicated that Pd-doped Co nanoparticles encapsulated in graphite carbon shell (Pd-doped CoNPs@C electrode) could be a very promising candidate for seawater electrolysis.

Green synthesis of MnCo2O4 nanoparticles grown on 3D nickel foam as a self-supported electrode for oxygen evolution reaction

The development of effective and low-cost catalysts for the oxygen evolution reaction (OER) has become an effective and promising strategy for sustainable energy technologies. In this work, we report a synthesis route for preparing MnCo2O4 nanoparticles on nickel foam (Ni foam) through a facile sol-gel method using Flaxseed (Linum usitatissimum) as a polymerizing agent and subsequent an adapted hydrothermal process. Here, a large surface area was obtained due to the small particle size combined with the absence of binders to promote the adhesion of the active material on the substrate. Thus, this seems to be an interesting strategy to boost electrocatalytic reactions. The structural, microstructural, and surface properties of MnCo2O4 electrodes are investigated by XRD, FESEM, TEM, FTIR, Raman, and XPS analysis. This electrode exhibits an overpotential of 296 mV (at 25 mA cm−2 current density), a Tafel slope of 82 mV dec−1, and excellent electrochemical stability for 15 h. This approach combines the features of a green synthesis with an adapted hydrothermal route to offer the advantages of a controllable reaction process, with good reproducibility, ally to uniform particle size distribution, short reaction time, and, mainly, respect for the environment. This demonstrates great potential in reproducing effective OER electrocatalysts for future applications.

Nanocomposite of nickel benzene‐1,3,5‐tricarboxylic acid metal organic framework with multiwalled carbon nanotubes: A robust and effective electrocatalyst for oxygen evolution reaction in water splitting

In the current era, the development of robust, eco‐friendly, and highly efficient electrocatalysts for generating hydrogen energy by water electrolysis has become a major challenge. This work explains the electrocatalytic performance of cost‐effective and amiable novel Ni‐BTC‐MWCNTs‐a as an active and effective electrocatalyst for OER in alkaline media. The catalytic activity of the nanocomposite is increased by heat treatment at 400°C temperature for 3 h. Systematic morphological and structural characterization studies of solvothermal synthesized materials were carried out by X‐ray powder diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy technique, scanning electron microscopy (SEM) analysis, and energy dispersive X‐ray spectroscopy (EDS) analysis techniques. Metal–organic framework (MOF)‐based composites exhibit improved catalytic performance owing to the synergistic effect of Nickel BTC MOF, MWCNTs support, and high‐temperature annealing (400°C). Among all as‐synthesized materials, the annealed Ni‐BTC‐MWCNT‐a exhibits admirable catalytic performance for oxygen evolution reaction (OER) at low value for over potential (η) 243 m V, small Tafel slope value 57 mV dec−1, smaller charge transfer resistance (0.274 Ω), and higher electrochemical active surface area (2000 cm2) with maximum durability for 23 h and utilized as auspicious alternate with excellent catalytic activity in water splitting OER process for producing hydrogen energy at large scale other than highly expensive electrocatalysts of Ir, Ru, Pd, and Pt oxides.

Incorporation of Bismuth Increases the Electrocatalytic Activity of Cobalt Borates for Oxygen Evolution Reaction.

The development of durable and efficient electrocatalysts composed of low-cost, earth-abundant metals for the oxygen evolution reaction (OER) is crucial for industrial-scale water splitting to produce green hydrogen on a large scale. Transition metal borates are considered good candidate electrocatalysts for OER due to their low cost, ease of synthesis, and good catalytic activity. In this work, we demonstrate that the incorporation of an oxophilic main group metal, bismuth (Bi), into cobalt borates produces highly effective electrocatalysts for OER. We also show that the catalytic activity of Bi-doped cobalt borates can be improved further by pyrolyzing them in an argon atmosphere. During pyrolysis, the Bi crystallites formed in the materials melt, transform into amorphous phases, interact better with the Co or B atoms in there, and form more synergistic catalytic sites for OER. By varying the amount of Bi as well as the pyrolysis temperature, different Bi-doped cobalt borates are synthesized, and the most optimal OER electrocatalyst is identified. Among them, the one with Co : Bi ratio of 9 : 1 and that is pyrolyzed at 450 °C exhibits the best catalytic activity, driving the reaction at a current density of 10 mA cm-2 with the lowest overpotential (318 mV) and a Tafel slope of 37 mV dec-1 .

Chromium doping enabled improvement in alkaline seawater oxidation over cobalt carbonate hydroxide nanowire array.

The presence of chlorine species in seawater can cause severe anode corrosion, highlighting the critical need for the design of efficient and robust electrocatalysts towards the oxygen evolution reaction (OER) for hydrogen production. Herein, we present a chromium doped cobalt carbonate hydroxide nanowire array on nickel foam (Cr-CoCH/NF) as an effective OER electrocatalyst in seawater. In alkaline conditions, Cr-CoCH/NF exhibits a low overpotential of 450 mV to achieve 500 mA cm-2, surpassing that of CoCH/NF (614 mV). Additionally, it demonstrates 200 h of continuous oxygen evolution testing.

Ni3C MXene nanosheets as an efficient binder-less electrocatalyst for oxygen evolution reaction

Low overpotential driven water-splitting is globally proposed as an effective replacement of conventional energy generation devices. However, these applications are extensively reported with noble electrocatalysts which makes them unsuitable for large scale applications. Therefore, it is essential to develop a non-noble, highly stable and low-cost electrocatalyst for oxygen evolution reaction (OER). In this report, we demonstrate solvothermal HF free etching and exfoliation of Ni-MAX to form Ni-MXene nanosheets as an effective electrocatalyst for OER. The as-synthesized Ni-MXene catalyst over nickel foam NiMX/NF electrode exhibits an overpotential of 245 mV at 100 mA/cm2. This performance can be attributed to the increased electrocatalytic activity and enhanced conductivity of the catalyst due to the presence of Ni2+/3+ redox couple and carbon in the Ni-MXene nanosheets, respectively. The catalyst electrode exhibits 83 % of current density retention after 14 h of continuous catalysis. This proves Ni MXene as an ideal candidate for the large scale and industrial applications of OER.

Interfacing CrOx and CuS for synergistically enhanced water oxidation catalysis

The sluggish kinetics associated with the oxygen evolution reaction (OER) limits the sustainability of fuel production and chemical synthesis. Developing catalysts based on Earth abundant elements with a reasonable strategy could solve the challenge. Here, we present a heterostructure built from CrOx and CuS whose interface gives rise to the advent of new functionalities in catalytic activity. Using X-ray photoelectron and absorption spectroscopies, we identified the multiple oxidation states and low coordination number of Cr metal in CrOx-CuS heterostructure. Benefitting from these features, CrOx-CuS generates oxygen gas through water splitting with a low over potential of 190 mV vs RHE at a current density of 10 mA cm−2. The catalyst shows no evident deactivation after a 36-hours operation in alkaline medium. The high catalytic activity, inspired by first principles calculations, and long-time durability make it one of the most effective OER electrocatalysts.

Metal-Functionalized Hydrogels as Efficient Oxygen Evolution Electrocatalysts.

Conductive polymer hydrogels have large surface areas and electrical conductivities. Their properties can be further tailored by functionalizing them with metals and nonmetals. However, the potential applications of metal-functionalized hydrogels for electrocatalysis have rarely been investigated. In this work, we report the synthesis of transition-metal-functionalized polyaniline-phytic acid (PANI-PA) hydrogels that show efficient electrocatalytic activities for the oxygen evolution reaction (OER). Among the many transition metals studied, Fe is accommodated by the hydrogel the most due to the favorable affinity of the PA groups in the hydrogel for Fe. Meanwhile, those containing both Fe and Co are found to be the most effective electrocatalysts for OER. The most optimized such hydrogel, NF@Hgel-Fe0.3Co0.1, which is made using a solution that has a 3:1 ratio of Fe and Co, needs an overpotential of only 280 mV to catalyze OER in 1 M KOH solution with a current density of 10 mV cm-2. Furthermore, these metal-functionalized PANI-PA hydrogels can easily be loaded on the nickel foam or carbon cloth via a simple soak-and-dry method to generate free-standing electrodes. Overall, this work demonstrates a facile synthesis and fabrication of sustainable and efficient OER electrocatalysts and electrodes that are composed of easily processable hydrogels functionalized with earth-abundant transition metals.

Comparison of hydrothermal and electrodeposition methods for the synthesis of CoSe2/CeO2 nanocomposites as electrocatalysts toward oxygen evolution reaction

Promoting efficacious and low-cost catalysts for the oxygen evolution reaction (OER), as the sluggish half-reaction of the water splitting, is inevitable to make sustainable energy technologies more promising. In this work, we report a series of novel nanocomposites comprising CeO2 nanorods decorated with CoSe2 nanoparticles. The nanocomposites were prepared via a conventional hydrothermal synthesis or a rapid electrodeposition process, and their structure, morphology, and electrochemical performance toward OER in alkaline solution were compared. To tune the electrocatalytic activity, the mass ratio of CoSe2 to CeO2 was systematically varied. Compared with the hydrothermal synthesis, the much faster electrodeposition method yielded a nanocomposite with a similar or slightly better performance in OER. This nanocomposite exhibited an overpotential of 290 mV (at 10 mA cm−2 current density), a Tafel slope of 53 mV dec−1, and excellent electrochemical stability for 15 h. Overall, these findings demonstrate the great potential of CoSe2/CeO2 nanocomposites as effective OER electrocatalysts for future applications.

Fe-Ni co-doping strategy in perovskite for developing an efficient oxygen evolution electrocatalyst

The high reaction barrier of the oxygen evolution reaction (OER) has always been the bottleneck of the water decomposition reaction, so low-cost, high-performance and stable catalysts are urgently needed currently. Herein, we designed an effective OER electrocatalyst BaCo0.6Fe0.2Ni0.2O3−δ (BCFN) by a codoping strategy. The overpotential of BCFN at a current density of 10 mA/cm2 reaches 310 mV, and possesses a Tafel slope of 50.2 mV/dec. The catalytic capability of BCFN is much stronger than that of Fe-doped BaCo0.8Fe0.2O3−δ (360 mV), Ni-doped BaCo0.8Ni0.2O3−δ (375 mV), and benchmark IrO2 with excellent performance (329 mV). At the same time, BCFN is also a fairly stable alkaline OER catalyst. After 500-cycle scans, BCFN still shows high catalytic activity without significant decrease in catalytic performance. Electrochemical experiments show that BCFN has the fastest reaction kinetics and the lowest charge transfer resistance among the materials in this work. In addition, a large amount of highly oxidative oxygen O22−/O− and hydroxyl groups OH− on the surface of BCFN are conducive to the occurrence of OER, thereby increasing the reaction rate. This work provides a universal strategy to develop high-performance electrocatalysts for electrochemical energy conversion technology.

Ce and MoS2 dual-doped cobalt aluminum layered double hydroxides for enhanced oxygen evolution reaction

Element doping has become an important means of designing and developing efficient and stable Oxygen Evolution Reaction (OER). In this work, a new type of CoAl LDH doped with Ce and MoS2 was designed and prepared. The catalyst first prepared Ce-doped CoAl LDH (Ce–CoAl LDH) by co-precipitation and one-step hydrothermal method. Then, MoS2 was introduced between Ce–CoAl LDH layers by hydrothermal method. The double doping of Ce and MoS2 could significantly improve the electrocatalytic activity of CoAl LDH. At the current density of 10 mA/cm2, the potential of 5% Ce–CoAl LDH@MoS2 is 1.508 V, which is much lower than the 1.733 V of CoAl LDH. And the ECSA of 5% Ce-CoAL LDH@MoS2 (23.4 mF/cm2) is nearly 8 times that of CoAl LDH (7.9 mF/cm2). Its excellent OER performance benefits from the increase of active sites and the enhancement of conductivity. This work provides a new research idea for doping design of effective OER electrocatalysts.

Core-shell trimetallic NiFeV disulfides and amorphous high-valance NiFe hydroxide nanosheets enhancing oxygen evolution reaction

Developing highly efficient, stable, and earth-abundant heterogeneous electrocatalysts for the oxygen evolution reaction (OER) is a significant challenge. Herein, we designed and synthesized a novel core–shell trimetallic Ni0.70Fe0.10V0.20S2 @ amorphous NiFe hydroxide for enhancing OER kinetics using thermal sulfidation and in situ electrochemical tuning methods. Electrochemical testing of various as-prepared catalysts at the same mass loading demonstrated that the trimetallic Ni0.70Fe0.10V0.20S2 @ amorphous NiFe hydroxide possessed the highest intrinsic activity for the OER compared to other reference catalysts. Furthermore, the heterostructures are directly grown on a carbon paper with a high surface area and good conductivity to form an integrated 3D electrode with an overpotential of 204 mV at the current density of 10 mA cm-2 and a small Tafel slope of 39 mV dec-1 in 1.0 M KOH electrolyte. This is one of the most effective OER electrocatalysts. X-ray photoelectron spectroscopy and scanning electron microscopy indicated that the material structure and chemical composition of Ni0.70Fe0.10V0.20S2 @ amorphous NiFe hydroxide exhibited good stability under harsh OER conditions. These advantages could be mainly attributed to the synergistic effect between the core and shell, high electronic conductivity of the core, and more active sites on the surface of the amorphous shell. Additionally, this study provides novel insights for designing and synthesizing heterostructure multimetallic disulfides electrocatalysts for OER in the future.

Machine learning-accelerated prediction of overpotential of oxygen evolution reaction of single-atom catalysts

SummaryThe oxygen evolution reaction (OER) is a critical reaction for energy-related applications, yet suffers from its slow kinetics and large overpotential. It is desirable to develop effective OER electrocatalysts, such as single-atom catalysts (SACs). Here, we demonstrate machine learning (ML)-accelerated prediction of OER overpotential of all transition metals. Based on density functional theory (DFT) calculations of 15 species of SACs, we design a topological information-based ML model to map the OER overpotentials with atomic properties of the corresponding SACs. The trained ML model not only yields remarkable prediction precision (relative error of 6.49%) but also enables a 130,000-fold reduction of prediction time in comparison with pure DFT calculation. Furthermore, an intrinsic descriptor that correlates the overpotential of an SAC with its atomic properties is revealed. The approach and results from this study can be readily applicable to screen other SACs and significantly accelerate the design of high-performance catalysts for many other reactions.

Cactus-like NiCo2S4@NiFe LDH hollow spheres as an effective oxygen bifunctional electrocatalyst in alkaline solution

The high-performance non-precious electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial to the practical application of fuel cells and metal-air batteries. Herein, a novel cactus-like NiCo2S4@NiFe LDH hollow sphere assembled by one-dimensional (1D) NiFe LDH nanowires and two-dimensional (2D) NiFe LDH nanosheets on the NiCo2S4 hollow spheres is prepared by a facile hydrothermal method. The outer NiFe LDH nanowires and NiFe LDH nanosheets can effectively suppress the collapse and corrosion of inner NiCo2S4 hollow structure during long-term stability tests. The integration of the effective OER electrocatalyst NiFe LDH into NiCo2S4 to form heterostructures, as well as the strong electronic interaction between NiCo2S4 and NiFe LDH, can greatly boost both ORR and OER activities. Due to the above merits, the NiCo2S4@NiFe LDH achieves remarkably a small potential gap (ΔE = Ej=10-E1/2) of only 0.667 V. This work offers a facile strategy to design efficient catalysts with heterostructures.

Boosting Oxygen Evolution Reaction Using Defect Rich Ultra-Thin Ruthenium Oxide Nanosheets in Acidic Media

Hydrogen is regarded as the most promising energy carrier. The pure hydrogen produced from electrochemical water splitting by using renewable energy is the most attractive and effective approach.[1] In comparison to alkaline water electrolysis, proton exchange membrane water electrolyzers (PEMWEs) could operate at higher current densities, lower ohmic loss, more compact system design, faster system response and more stable towards load-cycling and shutdowns. [2] The sluggish kinetics of oxygen evolution reaction (OER) at the anode of PEMWEs has restricted its practical applications. To date, iridium (Ir) metal and its oxide are usually selected as the state-of-the-art catalyst for OER due to their robust and long-term durability under the harsh acidic conditions. Nevertheless, Ir is an extremely scarce element, and its price has been doubled in the past few years. The development of low cost and highly effective electrocatalyst for OER in an acidic medium is urgently needed but remains a great challenge.In this work, we have prepared an ultra-thin RuO2 nanosheets by a simple molten salt method. High resolution STEM results show that the as-prepared RuO2 nanosheets is about 1-2 nm in thickness and hold a large number of defects, like Ru vacancy, grain boundary and amorphous. Toward OER, the as-prepared RuO2 nanosheets demonstrate an outstanding OER activity in acidic electrolyte, with an overpotential of only 199 mV for reach the current density of 10 mA cm-2 geo at a catalyst loading of 125 μg cm-2 geo. At the overpotential of 230 mV, the specific and mass activities of RuO2 nanosheets electrode is up to 0.89 mA cm-2 oxide and 0.516 A mg-1 Ru, which is 14.9 and 80.5 times higher than that of commercial RuO2 catalyst, respectively. Density functional theory (DFT) calculations (Figure 2e and 2f) indicated that the Ru vacancy defect on RuO2 surface could servers as the highly active site for remarkably weaken the binding energies of *O as compared to that of *OOH, which decrease the energy gap between ΔGO and ΔGOOH and thus dramatic enhanced OER performance. We also applied the catalysts in a homemade PEMWE device, at the applied cell voltage of 1.65 V, the current density of the RuO2 nanosheets catalyst cell reaches 0.93 A cm-2, which is almost 3 times larger than that of the cell with commercial RuO2 catalyst (0.31 A cm-2) at the same conditions, demonstrating that the RuO2 nanosheets possess great potential toward developing high performance PEMWEs.This work is under progress. Meanwhile, further characterizations, including XRD, XPS and more detailed morphology and electrochemical performance characterization of the RuO2 nanosheets catalyst will be presented at the meeting.The work described in this paper was financially supported by the Shenzhen Clean Energy Research Institute (No. CERI-KY-2019-003), Shenzhen Peacock Plan (KQTD2016022620054656), Shenzhen Key Laboratory project (ZDSYS201603311013489), The authors acknowledge the assistance of SUSTech Core Research Facilities.