Stable Electrocatalysts Research Articles

The Reconstruction of Bi2Te4O11 Nanorods for Efficient and pH-universal Electrochemical CO2 Reduction.

The electrochemical CO2 reduction reaction (CO2RR) to generate chemical fuels such as formate presents a promising route to a carbon-neutral future. However, its practical application is hindered by the competing CO production and hydrogen evolution reaction (HER), as well as the lack of pH-universal catalysts. Here, Te-modified Bi nanorods (Te-Bi NRs) were synthesized through in situ reconstruction of Bi2Te4O11 NRs under the CO2RR condition. Our study illustrates that the complex reconstruction process of Bi2Te4O11 NRs during CO2RR could be decoupled into three distinct steps, i.e., the destruction of Bi2Te4O11, the formation of Te/Bi phases, and the dissolution of Te. The thus-obtained Te-Bi NRs exhibit remarkably high performance in CO2RR towards formate production, showing high activity, selectivity, and stability across all pH conditions (acidic, neutral, and alkaline). In a flow cell reactor under neutral, alkaline, or acidic conditions, the catalysts achieved HCOOH Faradaic efficiencies of up to 94.3 %, 96.4 %, and 91.0 %, respectively, at a high current density of 300 mA cm-2. Density functional theory calculations, along with operando spectral measurements, reveal that Te manipulates the Bi sites to an electron-deficient state, enhancing the adsorption strength of the *OCHO intermediate, and significantly suppressing the competing HER and CO production. This study highlights the substantial influence of catalyst reconstruction under operational conditions and offers insights into designing highly active and stable electrocatalysts towards CO2RR.

The Reconstruction of Bi2Te4O11 Nanorods for Efficient and pH‐universal Electrochemical CO2 Reduction

AbstractThe electrochemical CO2 reduction reaction (CO2RR) to generate chemical fuels such as formate presents a promising route to a carbon‐neutral future. However, its practical application is hindered by the competing CO production and hydrogen evolution reaction (HER), as well as the lack of pH‐universal catalysts. Here, Te‐modified Bi nanorods (Te−Bi NRs) were synthesized through in situ reconstruction of Bi2Te4O11 NRs under the CO2RR condition. Our study illustrates that the complex reconstruction process of Bi2Te4O11 NRs during CO2RR could be decoupled into three distinct steps, i.e., the destruction of Bi2Te4O11, the formation of Te/Bi phases, and the dissolution of Te. The thus‐obtained Te−Bi NRs exhibit remarkably high performance in CO2RR towards formate production, showing high activity, selectivity, and stability across all pH conditions (acidic, neutral, and alkaline). In a flow cell reactor under neutral, alkaline, or acidic conditions, the catalysts achieved HCOOH Faradaic efficiencies of up to 94.3 %, 96.4 %, and 91.0 %, respectively, at a high current density of 300 mA cm−2. Density functional theory calculations, along with operando spectral measurements, reveal that Te manipulates the Bi sites to an electron‐deficient state, enhancing the adsorption strength of the *OCHO intermediate, and significantly suppressing the competing HER and CO production. This study highlights the substantial influence of catalyst reconstruction under operational conditions and offers insights into designing highly active and stable electrocatalysts towards CO2RR.

Free-standing FeNiCuCoBMo high-entropy alloy bifunctional electrocatalysts for efficient pH-universal water electrolysis

Utilizing the synergistic effects of multi-components has been proven to be a feasible approach to enhance water splitting electrocatalytic activity, since developing efficient and stable bifunctional electrocatalysts within a wide pH range remains a significant challenge. Herein, we report a FeNiCuCoBMo high-entropy alloy (HEA) prepared by dealloying, showing outstanding bifunctional electrocatalytic performance for HER and OER in a pH-universal electrolyte. After dealloying for 7 h, the HER and OER overpotentials of the HEA strips in 1.0 M KOH decreased by 22 mV and 25 mV, respectively.Impressively, the free-standing strips with the optimal compositions achieve low HER (82 mV in acid and 101 mV in alkali at 10 mA·cm−2) and OER (311 mV in acid and 245 mV in alkali at 10 mA·cm−2) overpotentials. In a full hydrolysis experiment, a current of 10 mA·cm−2 can run for 100 h with only 1.58 V, which is attributed to the ample exposure of highly active sites resulting from the synergistic effect of each element. Theoretical calculations further support these findings, showing that the electronegativity differences of the metallic elements in FeNiCuCoBMo result in abnormal activity at specific locations (Fe and Mo).Additionally, charge rearrangement and enhanced electronic conduction at the interface reduce the activation energy barrier, thereby improving the performance of the electrocatalysts.

A facile strategy for synthesis of flower-like FeNiS2 nanocomposite via integration of binary metal-organic framework and metal sulfide for enhanced electrocatalytic oxygen evolution reaction

Researchers are looking into boosted functional materials to address the rising demand for enhanced energy storage and efficient catalysts in producing and storing sustainable energy. Here, we report the development of an integrated binary metallic FeNi metal-organic framework (MOF) through a unique method termed reductive electrosynthesis. This MOF provides customized catalytic sites inside a highly porous material by connecting metal cations via 2-amino terephthalic acid connectors. However, the poor electrical conductivity and stability of pristine MOFs have made their practical implementation difficult. A thin FeNiS2/nickel foam (NF) nanocomposite based on the precursor and self-sacrificed FeNi-MOF template was developed to get beyond these restrictions. In addition to improving electrical conductivity, this unique structure supports FeNi-MOF porous structure. As a result, the outstanding functional electrocatalytic performance of FeNiS2/NF on oxygen evolution reaction in alkaline media was observed at low overpotential of ηj10 = 280 mV and a tafel slope of 35 mV/dec. This study provides a feasible way to produce highly stable and active nonprecious electrocatalysts for commercial water electrolysis applications.

Electrochemical hydrogen production of SS, Ni, and Ni-B electrodes in prototype electrolyzer system

Highly efficient, low-cost, and stable electrocatalysts are crucial in electrocatalytic water splitting. Herein, the comparative study of stainless steel (SS), a Nickel (Ni/SS), and Nickel boride (Ni-B/SS) electrode for hydrogen production was carried out under a prototype electrolyzer system. The Ni/SS and Ni-B/SS were synthesized by a simple and low-cost chemical method on the SS substrate. As compared to SS and Ni/SS electrodes, the Ni-B/SS electrode demonstrates superior electrochemical activity towards the Hydrogen Evolution reaction (HER) with a low overpotential of 75 mV at a current density of 10 mA/cm2 and Tafel slope of 82 mV/dec in 1M KOH electrolyte. The as-fabricated Ni-B/SS electrode showed cauliflower-like morphology and exhibited an excellent hydrogen production rate such as 4.39 ml/min on a (2 cm x 2 cm) electrode at a constant potential of 2.2 V in a prototype electrochemical hydrogen production setup. The stability of the Ni-B/SS (6 cm x 6 cm) electrode was also checked on a large-scale prototype electrolyzer setup for 50 hr at a constant potential.

Hydrogen production via alkaline seawater electrolysis using iron-doped nickel diselenide as an efficient bifunctional electrocatalyst

Green hydrogen production via seawater electrolysis is a promising pathway towards sustainable energy future. However, seawater splitting is hindered by the low stability and selectivity of electrocatalysts towards hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and faces severe electrode corrosion. Herein, we report the synthesis of highly active and durable Fe-doped nickel diselenide (Fe–NiSe2) nanoparticles supported on nickel foam as bifunctional electrocatalysts for efficient alkaline seawater electrolysis via an electrodeposition method followed by low-temperature annealing. The electrocatalytic properties of as-prepared Fe–NiSe2 toward HER and OER are investigated in different electrolytes. The optimized electrocatalyst (20-Fe-NiSe2) shows very low overpotential of 92 and 96 mV in alkaline (1.0 M KOH) and simulated seawater (1.0 M KOH + 0.5 M NaCl) electrolytes, respectively, to reach the current density of 10 mA cm−2 for HER. For the OER, 20-Fe-NiSe2 exhibits an overpotential of 333 and 311 mV in alkaline and simulated seawater electrolytes, respectively, to attain a current density of 100 mA cm−2. Further, full-cell studies are carried out with 20-Fe-NiSe2 as bifunctional electrocatalysts, which requires cell potential of 1.83 V and 1.81 V to deliver a current density of 100 mA cm−2 in alkaline and simulated seawater electrolytes, respectively. Additionally, the electrode shows tremendous potential for use in alkaline seawater electrolysis with stability over 100 h, at a current density of 100 mA cm−2, which is achieved at a low cell voltage of 1.87 V. The present work offers a simple, efficient, and cost-effective method for the development of heterogeneous Fe-doped nickel diselenide electrocatalysts for seawater electrocatalysis.

Evaluation of anion exchange membrane water electrolysis performance using synthesised NiMoO4/Ni cathode via solution combustion synthesis in applied thermal reduction approach

The development of sustainable electrocatalysts is essential for the advancement of anion exchange membrane water electrolysis (AEMWE) technologies. Nickel molybdate-based catalysts may improve the efficiency of hydrogen evolution reaction (HER) during alkaline water electrolysis. This study investigated the influence of thermal reduction temperature on the synthesised NiMoO4-based catalyst via solution combustion synthesis (SCS) and its performance in HER and single-cell AEMWE. The optimal conditions for stable and active HER electrocatalysts were determined by investigating synthesised NiMoO4 catalysts at 450 °C, 550 °C and 750 °C. A NiMoO4 catalyst was characterised at different reduction temperatures through X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS) and Brunauer–Emmett–Teller (BET) analysis. Results revealed that the NiMoO4-450/Ni cathode became the highest performance 1 A/cm2 current density at 2.2 V and the NiMoO4-550/Ni cathode became the most stable performance among the catalysts, attaining. The average current density of NiMoO4-550/Ni fluctuated by only 22% from 24 h to 100 h.

High efficiency conversion of low concentration nitrate boosted with amorphous Cu0 nanorods prepared via in-situ reconstruction

Electrocatalytic nitrate reduction reaction (NO3−RR) is a green and competitive method for removing nitrate from water, requiring highly active and long-term stable electrocatalysts. In this work, we report a Cu0 nanorod catalyst with disordered structure (re-Cu NRs), prepared by electrochemical in situ reconfiguration of copper-based nitrides (Cu3N NRs). The amorphous structure allows the exposure of abundant active sites to enhance the electrocatalytic activity because of the disordered atomic arrangement. At a potential of −1.2V vs. Ag/AgCl, the re-Cu NRs catalyst achieved nearly 100% nitrate conversion within 120 min at a low nitrate concentration (50 mg/L), without the accumulation of nitrite. In-situ DEMS detection reveals that the NO3−RR on re-Cu NRs followed the pathway of *NO3− → *NO2− → *NO → *N → *NH → *NH2 → *NH3. Furthermore, combining this proposed pathway with electrochlorination could efficiently transform ammonia into harmless N2 (∼99.41%). Theoretical calculations confirm that the amorphous structure on the surface of re-Cu NRs catalysts can facilitate strongly adsorbed nitrate, weaken the rate-determining step of *NH3 → NH3, and suppress Hydrogen evolution reaction (HER). This study provides a new approach for designing efficient and stable amorphous catalysts for electrocatalytic nitrate reduction.

Terbium- and samarium-doped Li2ZrO3 perovskite materials as efficient and stable electrocatalysts for alkaline hydrogen evolution reactions

The preparation of highly active, rare earth, non-platinum-based catalysts for hydrogen evolution reactions (HER) in alkaline solutions would be useful in realizing green hydrogen production technology. Perovskite oxides are generally regarded as low-active HER catalysts, owing to their unsuitable hydrogen adsorption and water dissociation. In this article, we report on the synthesis of Li2ZrO3 perovskites substituted with samarium and terbium cations at A-sites for the HER. LSmZrO3 (LSmZO) and LTbZrO3 (LTbZO) perovskite oxides are more affordable materials, starting materials in abundance, environmentally friendly due to reduced usage of precious metal and moreover have potential for several sustainable synthesis methods compared to commercial Pt/C. The surface and elemental composition of the prepared materials have been confirmed by X-ray photoelectron spectroscopy (XPS). The morphology and composition analyses of the LSmZO and LTbZO catalysts showed spherical and regular particles, respectively. The electrochemical measurements were used to study the catalytic performance of the prepared catalyst for hydrogen evolution reactions in an alkaline solution. LTbZO generated 2.52 mmol/g/h hydrogen, whereas LSmZO produced 3.34 mmol/g/h hydrogen using chronoamperometry. This was supported by the fact that the HER electrocatalysts exhibited a Tafel slope of less than 120 mV/dec in a 1.0 M alkaline solution. A current density of 10 mA/cm2 is achieved at a potential of less than 505 mV. The hydrogen production rate of LTbZO was only 58.55%, whereas LSmZO had a higher Faradaic efficiency of 97.65%. The EIS results demonstrated that HER was highly beneficial to both electrocatalysts due to the relatively small charge transfer resistance and higher capacitance values.

Spider silk inspired ultrafine carbon nanotubes-crosslinked porous carbon fibers for Zn-air batteries

There is a critical need for the development of low-cost, highly efficient, and stable bifunctional oxygen electrocatalysts for the advancement of Zn-air battery (ZAB). This study presents an Fe-, Ni-, and N-co-doped porous carbon material (FeNiN-CF-15) synthesized through the pyrolysis of a mixture combining the melamine and electrospun fibers. This material comprises carbon fiber substrates and spider silk-like ultrafine carbon nanotubes (CNTs) catalytically grown from FeNi alloys. With a high N doping level (12.9 at%), large specific surface area (385.18 m2 g−1), and conductive carbon network composed of CNTs, the new electrocatalyst exhibits outstanding bifunctional oxygen electrocatalytic performances. Specifically, it achieves a half-wave potential of 0.853 V for oxygen reduction reaction (ORR) and 1.571 V for oxygen evolution reaction (OER) at 10 mA cm−2. The exceptional ORR/OER electrocatalytic activity enables the FeNiN-CF-15-based liquid ZAB to deliver a high initial energy efficiency of 62.12 %, narrow charging/discharging voltage gap of 0.742 V, and robust cycling stability within 960 cycles for 320 h at 5 mA cm−2. Additionally, the reported electrocatalyst is proven competent for use in a flexible ZAB.

Microwave-edge-thermal effect induced growth of coral-like self-supporting CoFe2O4/NF electrocatalysts for efficient water splitting at high-current–density

High-efficiency and long-term water-splitting to produce hydrogen under the high-current–density (HCD) environment is a severe challenge because the swift-consumption of electrolyte and large-production of bubbles require better charge/mass-transfer capability and durability of electrocatalysts. Rationally design and effectively construct of three-dimensional (3D) hierarchical electrocatalysts is the promising solutions to accelerate the charge/mass transfer rates during water splitting process. Herein, a 3D self-supporting coral-like oxygen evolution reaction (OER) electrode was synthesized using a microwave-edge-thermal (MET) effect induced heterogeneous-nucleation/oriented-attachment growth process by in-situ growing CoFe2O4 nanocrystals on nickel-foams (CoFe2O4/NF). SEM, TEM, electrolyte/catalyst contact angles, in-situ observation of O2 bubbles generation-evolution process, and three-electrode configuration (TEC) and anion-exchange-membrane (AEM) electrocatalytic OER tests at the HCD were used to investigated the structure–activity relationship of the CoFe2O4/NF electrode. The CoFe2O4/NF electrode offered super hydrophilic/aerophobic surfaces and firmly bonded interfaces, resulting in quicker charge/mass-transfer rates and long-term durability under the HCD conditions. The typical electrode exhibited a low OER overpotential of 0.24 V at 10 mA cm−2 and a Tafel slope of 35.2 mV dec−1; its alkaline AEM electrolyzer (Pt || CoFe2O4/NF) yielded a HCD of 1200 mA cm−2 at only 2.36 V and 60˚C and kept stable over 120 h. This work provides a new insight into the design and fabrication of active and stable non-noble metal-based OER electrocatalysts for cost-effective water-electrolysis applications.

Nanoarchitectonics of few-layer Ni3Fe nanosheets embedded porous nitrogen-doped carbon derived from asphalt waste: An efficient electrocatalyst for oxygen evolution reaction

The design and fabrication of stable, high-performance, and affordable oxygen evolution reaction (OER) electrocatalysts is essential for performing practical water electrolysis and generating green hydrogen energy. Here, we report that 2D few layer Ni3Fe nanosheets embedded with 2D porous nitrogen doped carbon (N-NixFe@CF) from asphalt waste and then convolved and assembled into 1D hollow nanotube structures by Lewis acid molten salt etching method, which were used as electrocatalysts for OER. Benefiting from the integrate of 1D hollow nanotube structure and 2D porous nanosheets, the close contact between catalysts and support, and the increased conductivity, the resultant N-Ni3Fe@CF catalysts exhibited high catalytic activities in the OER with low overpotential at a current density of 10 mA cm−2 (114 mV), low Tafel slope (166.6 mV dec−1), and excellent electrochemical stability. This work provides a new concept for expanding the use of asphalt wastes and by-products, as well as a straightforward synthesis method for producing economical, efficient, and long-lasting alkaline OER electrocatalysts.

Revealing the role of 1T- & 2H- molybdenum Disulfide/Nickel sulfide heterojunction for efficient overall water splitting

In the ongoing quest for cost-effective and durable electrocatalysts for hydrogen production—a critical element of sustainable energy transformation—the 1T phase of Molybdenum Disulfide (MoS2) faces challenges due to its thermodynamic instability and the trade-off between efficiency and durability. Conversely, the 2H phase of MoS2, often disregarded in favor of the metallic 1T phase, suffers from its inert nature and limited active sites. To overcome these limitations, this study employs a straightforward hydrothermal synthesis strategy that couples both 1T and 2H phases of MoS2 with Ni3S2, forming 1T- and 2H- MoS2/Ni3S2 heterojunctions. Enhanced by Ni3S2′s abundant active sites, improved electron transport capabilities, synergistic interface effects, and better structural stability, these heterojunctions achieve a high current density exceeding 500 mA cm−2 at low overpotentials, along with prolonged durability for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolytes. Remarkably, an electrolyzer assembly utilizing 1T-MoS2/Ni3S2 as the cathode and 2H-MoS2/Ni3S2 as the anode demonstrates a competitive voltage of 1.58 V at 20 mA cm−2, showcasing superior performance in overall water splitting compared to other non-noble metal-based electrocatalysts. This study not only offers a viable method for synthesizing efficient and stable electrocatalysts for water splitting using transition metal-based heterogeneous structures but also addresses the fundamental challenges associated with 1T and 2H phases of MoS2.

Scaling Up Stability: Navigating from Lab Insights to Robust Oxygen Evolution Electrocatalysts for Industrial Water Electrolysis

AbstractIn the pursuit of sustainable hydrogen production via water electrolysis, paramount importance of electrocatalyst stability emerges as a defining factor for long‐term industrial viability. A thorough understanding and enhancement of stability not only ensure extended catalyst lifetimes but also pave the way for consistent and efficient hydrogen generation. This review focuses on the pivotal role of stability in determining the practical viability of oxygen evolution electrocatalysts (OECs) for large‐scale applications in water electrolysis for hydrogen production. The paper explores the pivotal role of stability over initial activity, citing examples and hypothetical scenarios. First, figures of merits for stability evaluation of the electrocatalyst are explained along with the available benchmarking protocols for stability evaluation. Further, the text delves into various strategies that can enhance the stability of the electrocatalyst which include self‐healing/regeneration pathway, oxygen evolution reaction (OER) mechanism optimization to achieve highly stable OER and stabilization of active metals atoms within the electrocatalyst to inhibit dissolution as a way forward for industrial application. The interplay of stability, activity, and cost is also explained to suit the industrial application of the electrocatalyst. Lastly, it outlines challenges, prospects, and future directions, presenting a guide for advancing OECs in the hydrogen generation landscape.

Factors influencing the stability of Pt-based ORR electrocatalysts in HT-PEMFCs: A theoretical investigation

Electrocatalyst stability is a key parameter for commercializing high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). Here, we used density functional theory (DFT) to investigate the stability of Pt-based electrocatalysts by calculating the binding energy (ΔEb) of surface Pt atoms under working conditions. Our results show that Pt(111) is more stable than Pt(100) and Pt(110) under vacuum conditions. Stress hurts the stability of Pt(111), regardless of compressive or tensile stress. Most of the transition metals alloyed with Pt improve the stability of Pt(111), especially PtV, PtY, and PtTa, which increase the ΔEb by 0.60–0.70 eV (ΔΔEb). However, the stability of Pt is significantly destroyed under the working conditions of oxygen reduction reaction (ORR). The specific adsorption of ORR intermediates and electrolyte ions decreases the ΔEb of Pt(111) by 0.35–0.95 eV, and the effect of PO43-* is more significant. Furthermore, when the electric field of the electrochemical double layer is coupled with PO43-* specific adsorption, ΔΔEb further increases to 1.12 eV. Our results highlight the importance of the intrinsic ΔEb and the working conditions for the stability of Pt-based electrocatalysts. This work provides important guidelines for the design of stable ORR electrocatalysts for HT-PEMFCs.

Metal–Organic Frameworks as a Catalyst and Catalyst Support in Fuel Cells: From Challenges to Catalytic Application

AbstractThe innovation of high‐performance, stable electrocatalysts for clean energy systems faces significant challenges. Metal‐organic frameworks (MOFs), with their porous nature, flexible structures, and homogeneous active site dispersion, have gained interest as unique precursors for carbon‐based catalysts. MOFs' properties significantly enhance catalytic performance in fuel cells. This review highlights recent advancements in MOF design for oxygen electrocatalysis in fuel cells, while also discussing perspectives for future material innovations to improve catalytic activity in this emerging field.

Physical insight into the enhanced urea electrooxidation using Ni and Fe-based LDH, LDO, and hydroxides under different dissolved gas saturation conditions in electrolyte

The production of green hydrogen is one of the most demanding and challenging for modern technology. A promising and an effective approach is electrocatalytic anodic urea oxidation reaction to generate hydrogen at cathode under alkaline electrolysis condition. However, it remains crucial for the development of active and stable electrocatalysts for efficient urea oxidation. In this study, we employed the hydrothermal synthesis route for NiFe LDH, NiFe LDO, and Ni(OH)2. The superior performance of NiFe LDH compared to other catalysts is observed due to easy charge transfer facilitated by Fe ions. Moreover, Fe incorporation prevents surface poisoning of the electrocatalyst, resulting in increased activity and stability for electrocatalytic urea oxidation reaction. The influence of different electrolyte environments on the performance of urea-based electrolyzers for sustainable hydrogen production and management of urea-rich wastewater has been measured for the first time by varying oxygen saturation and nitrogen purging conditions. In cyclic voltammetry studies, O2-saturated and purging conditions outperformed N2 gas saturation or purging. The findings of this study provide valuable insight into the design of practical and environmentally friendly urea electrooxidation systems.

Engineered CoS/Ni3S2 Heterointerface Catalysts Grown Directly on Carbon Paper as an Efficient Electrocatalyst for Urea Oxidation

Developing highly efficient and stable electrocatalysts for urea electro-oxidation reactions (UORs) will improve wastewater treatment and energy conversion. A low-cost cobalt sulfide-anchored nickel sulfide electrode (CoS/Ni3S2@CP) was synthesized by electrodeposition in DMSO solutions and found to be highly effective and long-lasting. The morphology and composition of catalyst surfaces were examined using comprehensive physicochemical and electrochemical characterization. Specifically, CoS/Ni3S2@CP electrodes require a potential of 1.52 volts for a 50 mA/cm2 current, confirming CoS in the heterointerface CoS/Ni3S2@CP catalyst. Further, the optimized CoS/Ni3S2@CP catalyst shows a decrease of 100 mV in the onset potential (1.32 VRHE) for UORs compared to bare Ni3S2@CP catalysts (1.42 VRHE), demonstrating much greater performance of UORs. As compared to Ni3S2@CP, CoS/Ni3S2@CP exhibits twofold greater UOR efficiency as a result of a larger electroactive surface area. The results obtained indicate that the synthetic CoS/Ni3S2@CP catalyst may be a favorable electrode material for managing urea-rich wastewater and generating H2.

Electrocatalytic ammonia synthesis on bimetallic AuPd porous structures

In industry, production of ammonia mainly relies on the intensive Haber-Bosch process, but it consumes high energy with low efficiency and generates a large number of green-house gases. Electrocatalytic nitrogen reduction reaction (ENRR), as an alternative method for fixing N2 under ambient conditions, provides a feasible strategy for sustainable development of N2 cycle storage and utilization of renewable energy. However, traditional nanocatalysts exhibit extremely poor ENRR performance due to low activity of the solid structure and intense hydrogen evolution reactions of single component. Herein, we design and prepare porous gold–palladium nanoalloys (pAuPdNs), which effectively enhance ENRR by the excellent catalytic activity of Au and the significant N2 fixation ability of Pd, as well as the nanoporous structure and synergistic effect between alloy components. The electrochemical results show the NH3 yield of the catalyst is as high as 43.6 μg·h−1·cm−2, and Faradaic efficiency reaches 43.8%, which are superior to the performances of most reported water-based ENRR electrocatalysts. Besides, the selectivity of 95% and stability also exhibit enhancement than numerous reported researches. As compared with solid alloy and porous Au or Pd structures, the superiority of pAuPdNs states the influence of alloying and porous structure. Hence pAuPdNs are proved to be the efficient, stable, and promising electrocatalysts for N2 reduction reaction at ambient temperature and atmospheric pressure.

Chemical Epitaxy of Iridium Oxide on Tin Oxide Enhances Stability of Supported OER Catalyst.

Significantly reducing the iridium content in oxygen evolution reaction (OER) catalysts while maintaining high electrocatalytic activity and stability is a key priority in the development of large-scale proton exchange membrane (PEM) electrolyzers. In practical catalysts, this is usually achieved by depositing thin layers of iridium oxide on a dimensionally stable metal oxide support material that reduces the volumetric packing density of iridium in the electrode assembly. By comparing two support materials with different structure types, it is shown that the chemical nature of the metal oxide support can have a strong influence on the crystallization of the iridium oxide phase and the direction of crystal growth. Epitaxial growth of crystalline IrO2 is achieved on the isostructural support material SnO2, both of which have a rutile structure with very similar lattice constants. Crystallization of amorphous IrOx on an SnO2 substrate results in interconnected, ultrasmall IrO2 crystallites that grow along the surface and are firmly anchored to the substrate. Thereby, the IrO2 phase enables excellent conductivity and remarkable stability of the catalyst at higher overpotentials and current densities at a very low Ir content of only 14 at%. The chemical epitaxy described here opens new horizons for the optimization of conductivity, activity and stability of electrocatalysts and the development of other epitaxial materials systems.