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The design of high‐entropy single‐atom catalysts (HESAC) with 5.2 times higher entropy compared to single‐atom catalysts (SAC) is proposed, by using four different metals (FeCoNiRu‐HESAC) for oxygen reduction reaction (ORR). Fe active sites with intermetallic distances of 6.1 Å exhibit a low ORR overpotential of 0.44 V, which originates from weakening the adsorption of OH intermediates. Based on density functional theory (DFT) findings, the FeCoNiRu‐HESAC with a nitrogen‐doped sample were synthesized. The atomic structures are confirmed with X‐ray photoelectron spectroscopy (XPS), X‐ray absorption (XAS), and scanning transmission electron microscopy (STEM). The predicted high catalytic activity is experimentally verified, finding that FeCoNiRu‐HESAC has overpotentials of 0.41 and 0.37 V with Tafel slopes of 101 and 210 mVdec−1 at the current density of 1 mA cm−2 and the kinetic current densities of 8.2 and 5.3 mA cm−2, respectively, in acidic and alkaline electrolytes. These results are comparable with Pt/C. The FeCoNiRu‐HESAC is used for Zinc–air battery applications with an open circuit potential of 1.39 V and power density of 0.16 W cm−2. Therefore, a strategy guided by DFT is provided for the rational design of HESAC which can be replaced with high‐cost Pt catalysts toward ORR and beyond. [ABSTRACT FROM AUTHOR]

Here,nonprecious high‐entropy chalcogenide glasses (N‐HECGs) consisting of Co, Fe, Ni, Mo, W, and Te are demonstrated in a first demonstration of acidic oxygen evolution reaction (OER). N‐HECGs electrocatalysts with high activity and stability are synthesized using a hierarchical hybrid approach based on a combination of electrochemical deposition and tellurization process. The as‐prepared CoFeNiMoWTe N‐HECGs electrocatalysts exhibit an amorphous, porous structure of arrayed nanosheets with abundant active sites and the increased valence states of metal cations due to the incorporated non‐metallic Te, enabling the enhancement of glass forming ability and the valence states of metal elements. Thanks to the combination of their unique geometrical and chemical structure, as well as high configuration entropy nature and high corrosion‐resistance ability, the resultant CoFeNiMoWTe N‐HECGs exhibit excellent acidic OER catalytic performance with a superior overpotential of 373 mV and outstanding stability of 100 h at the current density of 10 mA cm−2 in 0.5 m H2SO4. Moreover, the CoFeNiMoWTe‐based proton exchange membrane water electrolyzer is demonstrated to require a cell voltage of 1.81 V at 70 °C to obtain the practically high current density of 1 A cm−2, and exhibits remarkably long‐term stability for 100 h with small potential degradation of only 30 mV. [ABSTRACT FROM AUTHOR]

In general, commercial ZnO owns the poor selectivity and activity toward electroreduction CO2 to formate. In contrast, the numbers of Sn‐based nanomaterials are reported as excellent electrocatalysts for formate production, however, the metallic Sn is more expensive than Zn. In this study, it is demonstrated that an atomically dispersed Sn on a tensile‐strained ZnO nanosheet (Sn SA/ZnO) shows dramatically improved activity and selectivity for formate production over a wide potential window compared with that of commercial ZnO. Especially, Sn SA/ZnO exhibits 205‐fold mass activity enhancement than the commercial Sn at −1.7 V versus reversible hydrogen electrode normalized with element Sn. The experimental measurements combined with theoretical calculations revealed that Sn SA/ZnO can effectively capture and activate CO2 by its exposed double‐active sites (Sn and O), while the tensile strain on its surface boosts the catalytic selectivity by strengthening the adsorption of the *HCOO intermediate for the electrochemical reduction of CO2 to formate. [ABSTRACT FROM AUTHOR]

NiFe‐based hydroxides are considered as promising nonprecious catalysts for water oxidation due to their low cost and easy preparation. However, the rational design of NiFe‐based electrocatalysts remains a great challenge to address the sluggish reaction kinetics and severe deactivation problems for oxygen evolution reaction (OER). Here, the authors report a facile approach to fabricate an amorphous Ce‐doped NiFe hydroxide catalyst, which enables high activity and outstanding stability toward OER in alkaline media. The overpotential of electrodeposited amorphous Ce‐doped NiFe is only 195 mV at 10 mA cm−2. Meanwhile, the durability of the amorphous Ce‐doped NiFe is maintained for 300 h at 100 mA cm−2. The comprehensive characterization results reveal that the improved electrochemical performance of the amorphous Ce‐doped NiFe catalyst is originated from the favorable oxidation transition of active sites enabled by Ce‐doping. It is a very good strategy to introduce highly oxidized state ions to regulate the NiFe‐based catalyst to improve the catalytic activity and stability. [ABSTRACT FROM AUTHOR]

Hydrogen generation by electrolysis of water in an alkaline solution is a promising technology for clean hydrogen energy. Amorphous materials show much better performance than their crystalline counterparts. However, it is still challenging to design amorphous metal materials. Here, a series of amorphous transition metal nanoparticles (NPs) is successfully synthesized using a twisted covalent organic network (CON) that can provide twisted carbon layers as well as asymmetrically distributed nitrogen. With the fixed monomer pore, a low loading amount of RuCl3 results in amorphous‐only Ru nanoclusters (NCs, 1.5 nm), while a high content of RuCl3 leads to crystalline dominant Ru NPs (3 nm). The mixed phased Ru‐CON catalyst for the hydrogen evolution reaction (HER) shows extremely low overpotential at 10 mA cm–2 (12.8 mV in 1.0 m KOH) and superior stability (after 100 h test, current loss 5.3% at 75 mA cm–2). More importantly, amorphous‐only Ru‐CON with smaller Ru NCs shows much better mass activity and considerable stability compared to mixed‐phase Ru‐CON materials since amorphous Ru NPs can provide more active sites than in their crystalline state. With this strategy, amorphous Fe NPs and Ir NPs are successfully prepared for extended applications, and the HER activities are reported. [ABSTRACT FROM AUTHOR]

Ru nanoparticles (NPs) and single atoms (SAs)‐based materials have been investigated as alternative electrocatalysts to Pt/C for hydrogen evolution reaction (HER). Exploring the dominant role of atomic‐ and nano‐ruthenium as active sites in acidic and alkaline media is very necessary for optimizing the performance. Herein, an electrocatalyst containing both Ru SAs and NPs anchored on defective carbon (RuSA+NP/DC) has been synthesized via a Ru–alginate metal–organic supramolecules conversion method. RuSA+NP/DC exhibits low overpotentials of 16.6 and 18.8 mV at 10 mA cm−2 in acidic and alkaline electrolytes, respectively. Notably, its mass activities are dramatically improved, which are about 1.1 and 2.4 times those of Pt/C at an overpotential of 50 mV in acidic and alkaline media, respectively. Theoretical calculations reveal that Ru SAs own the most appropriate H* adsorption strength and thus, plays a dominant role for HER in acid electrolyte, while Ru NPs facilitate the dissociation of H2O that is the rate‐determining step in alkaline electrolyte, leading to a remarkable HER activity. [ABSTRACT FROM AUTHOR]

Facilitating the dissociation of water and desorption of hydrogen are both crucial challenges for improving the hydrogen evolution reaction (HER) in alkaline media. Herein, we report the synthesis of heterostructure of Ru2P/WO3@NPC (N, P co‐doped carbon) by a simple hydrothermal reaction using ruthenium and tungsten salts as precursors, followed by pyrolyzing under an Ar atmosphere. The Ru2P/WO3@NPC electrocatalyst exhibits an outstanding HER activity with an overpotential of 15 mV at a current density of 10 mA cm−2 and excellent durability in a 1.0 M KOH solution, outperforming state‐of‐the‐art Pt/C and most reported electrocatalysts. Experimental results combined with density functional calculations reveal that the electron density redistribution in Ru2P/WO3@NPC is achieved by electron transfer from NPC to Ru2P/WO3 and from Ru2P to WO3, which directly promotes the dissociation of water on W sites in WO3 and desorption of hydrogen on Ru sites in Ru2P. [ABSTRACT FROM AUTHOR]

Developing highly active, durable, and cost‐effective electrocatalysts for the oxygen evolution reaction (OER) is of prime importance in proton exchange membrane (PEM) water electrolysis techniques. Herein, a surface lanthanum‐deficient (SLD) iridium oxide as a highly efficient OER electrocatalyst is reported (labeled as La3IrO7‐SLD), which is obtained by electrochemical activation, and shows better activity and durability than that of commerically available IrO2 as well as most of the reported Ir‐based OER electrocatalysts. At a current density of 10 mA cm−2, the overpotential of La3IrO7‐SLD is 296 mV, which is lower than that of IrO2 (316 mV). Impressively, the increase of potential is less than 50 mV at a voltage–time chronopotentiometry extending for 60 000 s using a glass carbon electrode that is vastly superior to IrO2. Moreover, the mass activity of the catalyst is approximately five times higher than that of IrO2 at 1.60 V versus reversible hydrogen electrode. Density functional theory calculations suggest that a lattice oxygen participating mechanism with central Ir atoms serving as active sites (LOM‐Ir) rationalizes the high activity and durability for the La3IrO7‐SLD electrocatalyst. The favorable energy level of surface active Ir 5d orbitals relative to coordinated O 2p orbitals makes the La3IrO7‐SLD more active. [ABSTRACT FROM AUTHOR]

A nanocomposite of PC/Sb/SbPO4 (PC, phosphorus‐doped carbon) exhibits a high activity and an excellent selectivity for efficient electrocatalytic conversion of N2 to NH3 in both acidic and neutral electrolytes under ambient conditions. At a low reductive potential of −0.15 V versus the reversible hydrogen electrode (RHE), the PC/Sb/SbPO4 catalyst achieves a high Faradaic efficiency (FE) of 31 % for ammonia production in 0.1 m HCl under mild conditions. In particular, a remarkably high FE value of 34 % is achieved at a lower reductive potential of −0.1 V (vs. RHE) in a 0.1 m Na2SO4 solution, which is better than most reported electrocatalysts towards the nitrogen reduction reaction (NRR) in neutral electrolyte under mild conditions. The change in surface species and electrocatalytic performance before and after N2 reduction is explored by an ex situ method. PC and SbPO4 are both considered as the active species that enhanced the performance of NRR. [ABSTRACT FROM AUTHOR]

Developing highly efficient and durable bifunctional electrocatalyst for oxygen reduction (ORR) and oxygen evolution reaction (OER) is quite important for developing rechargeable zinc‐air batteries. Herein, one kind of manganese phosphate‐based electrocatalyst (Mnx(PO4)y/NPC) with high specific surface area (1106.9 m2 g−1) is prepared via a facile and scalable avenue, which possesses remarkable catalytic performance for the both ORR and OER, indicated by a more positive half‐wave potential of 0.87 V in 0.1 M KOH for the ORR as well as an overpotential of 0.37 V to achieve the current density of 10 mA cm−2 in 1 M KOH for the OER. Furthermore, the Mnx(PO4)y/NPC assembled rechargeable zinc‐air battery shows an excellent charge‐discharge cycling performance, revealed by the smaller sum of charge‐discharge potentials, comparable to that of Pt/C+IrO2. This research adds a new kind of electrocatalyst into the family of non‐noble metal‐based bifunctional electrocatalyst for rechargeable zinc‐air batteries. Re‐charge ahead: Mnx(PO4)y/NPC exhibits excellent catalytic performance for both ORR and OER, which possesses more superior electrochemical performance than Pt/C for the application in zinc‐air battery. The specific approaches to 668 mA h gZn−1. This work provides a facile and efficient avenue to synthesize non‐precious electrocatalyst with bifunctional catalytic effects and using in rechargeable zinc‐batteries. [ABSTRACT FROM AUTHOR]

In this paper, Ni‐based titanate nanosheets are used as a model system to reveal how incorporation of Fe affects their catalytic ability for the oxygen evolution reaction (OER). The Fe incorporation effects are studied without structural and morphological changes due to the rigid framework of TiO2 based nanosheets. Transition metal doped titanate nanosheets are prepared by cation‐assisted exfoliation of protonated layered potassium titanate. Fe incorporation within the lattice of Ni doped titanate nanosheets by co‐doping stabilizes nickel ions in lower oxidation state by charge transfer effect, caused increased OER activity at Ni sites by the electronic interaction. In contrast, incorporation of Fe from the electrolyte, highly‐active Fe sites at edges or corners of Ni doped titanate nanosheets are formed by electrochemical cycling in Fe‐containing electrolyte rather than electronic effects on Ni. Through this work, Fe incorporation effects are experimentally revealed without crystal structural or morphological changes, and a method to produce a highly active and stable OER catalyst is provided. [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) along with hydrogen evolution reaction (HER) have been considered critical processes for electrochemical energy conversion and storage through metal-air battery, fuel cell, and water electrolyzer technologies. Here, a new class of multifunctional electrocatalysts consisting of dominant metallic Ni or Co with small fraction of their oxides anchored onto nitrogen-doped reduced graphene oxide (rGO) including Co-CoO/N-rGO and Ni-NiO/N-rGO are prepared via a pyrolysis of graphene oxide and cobalt or nickel salts. Ni-NiO/N-rGO shows the higher electrocatalytic activity for the OER in 0.1 m KOH with a low overpotential of 0.24 V at a current density of 10 mA cm−2, which is superior to that of the commercial IrO2. In addition, it exhibits remarkable activity for the HER, demonstrating a low overpotential of 0.16 V at a current density of 20 mA cm−2 in 1.0 m KOH. Apart from similar HER activity to the Ni-based catalyst, Co-CoO/N-rGO displays the higher activity for the ORR, comparable to Pt/C in zinc-air batteries. This work provides a new avenue for the development of multifunctional electrocatalysts with optimal catalytic activity by varying transition metals (Ni or Co) for these highly demanded electrochemical energy technologies. [ABSTRACT FROM AUTHOR]

The lack of high-efficient, low-cost, and durable bifunctional electrocatalysts that act simultaneously for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) is currently one of the major obstacles to commercializing the electrical rechargeability of zinc-air batteries. A nanocomposite CoO-NiO-NiCo bifunctional electrocatalyst supported by nitrogen-doped multiwall carbon nanotubes (NCNT/CoO-NiO-NiCo) exhibits excellent activity and stability for the ORR/OER in alkaline media. More importantly, real air cathodes made from the bifunctional NCNT/CoO-NiO-NiCo catalysts further demonstrated superior performance to state-of-the-art Pt/C or Pt/C+IrO2 catalysts in primary and rechargeable zinc-air batteries. [ABSTRACT FROM AUTHOR]

La0.3(Ba0.5Sr0.5)0.7Co0.8Fe0.2O3− δ is a promising bifunctional perovskite catalyst for the oxygen reduction reaction and the oxygen evolution reaction. This catalyst has circa 10 nm-scale rhombohedral LaCoO3 cobaltite particles distributed on the surface. The dynamic microstructure phenomena are attributed to the charge imbalance from the replacement of A-site cations with La3+ and local stress on Co-site sub-lattice with the cubic perovskite structure. [ABSTRACT FROM AUTHOR]