Ultrasmall size and abundant defects are two crucial factors for improving the performance of catalysts. However, it is a big challenge to introduce defects into ultrafine catalysts because of the surface tension and self-purification effect of the nanoparticles. In the present work, physical laser fragmentation with chemical oxidization reaction is combined to synthesize Co 3 O 4 nanoparticles (L-CO) with ultrasmall size (≈2.1 nm) as well as abundant oxygen vacancies, thus providing an effective solution to the long-standing contradiction between the size reduction and defect generation. The ultrasmall particle size allows more catalytic sites to be exposed. The surficial oxygen vacancies enhance the intrinsic activity, while the internal oxygen vacancies improve the electron transfer, and all of these benefits make L-CO an active and durable bifunctional catalyst for oxygen reduction/evolutions. As the air cathode of zinc-air battery, L-CO displays excellent rechargeable performance with a power density of ≈337 mW cm −2 , outperforming the commercial noble metal couple (Pt/C+RuO 2 ).

Water electrolysis in alkaline electrolyte is an attractive way toward clean hydrogen energy via the hydrogen evolution reaction (HER), whereas the sluggish water dissociation impedes the following hydrogen evolution. Noble metal oxides possess promising capability for catalyzing water dissociation and hydrogen evolution; however, they are never utilized for the HER due to the instability under the reductive potential. Here it is shown that compressive strain can stabilize RhO2 clusters and promote their catalytic activity. To this end, a strawberry‐like structure with RhO2 clusters embedded in the surface layer of Rh nanoparticles is engineered, in which the incompatibility between the oxide cluster and the metal substrate causes intensive compressive strain. As such, RhO2 clusters remain stable at a reduction potential up to −0.3 V versus reversible hydrogen electrode and present an alkaline HER activity superior to commercial Pt/C.

Electrocatalytic nitric oxide (NO) reduction represents a sustainable route from the point of view of environmental protection and ammonia generation. However, conversion from NO to ammonia under low NO concentrations is still a big challenge. Herein, Ru nanosheets with low coordination numbers (Ru-LCN) are prepared and exhibit high performance for electrocatalytic NO (1% v/v) reduction to ammonia under −0.2 V vs RHE (Faradaic efficiency, 65.96%; yield rate, 45.02 μmol•h −1 •mg cat −1 ), obviously outperforming its counterpart of high coordination number Ru nanosheets (Faradaic efficiency, 37.25%; yield rate, 25.57 μmol•h −1 •mg −1 ). Colorimetric methods and 1 H nuclear magnetic resonance spectroscopy are performed to quantify ammonia. Through the combination of online differential electrochemical mass spectrometry (DEMS) and electrochemical in situ Fourier transform infrared (FTIR) spectroscopy with density functional theory calculations, the possible reaction pathway and enhanced mechanism are revealed. Constructing low coordination number Ru active sites is conducive to facilitating the adsorption of NO and reducing the reaction energy barrier of the potential-determining hydrogenation step.

Highly effective catalysts are of great importance for artificial nitrogen fixation. Inspired by the natural nitrogenase, we biomimetically designed an inorganic catalyst, Mo­(IV)-doped FeS2, for electroreduction of dinitrogen to ammonia. The Mo­(IV) ions favor the adsorption and activation of N2, while the FeS2 substrate depresses the competitive hydrogen evolution reaction, and the two factors jointly endow the catalyst with a high Faraday efficiency of 14.41% at −0.2 V versus RHE.

The electrocatalytic nitrogen oxidation reaction (NOR) to generate nitrate is gaining increasing attention as an alternative approach to the conventional industrial manufacture. But, current progress in NOR is limited by the difficulties in activation and conversion of the strong N�N bond (941 kJ mol À 1 ). Herein, we designed to utilize sulfate to enhance NOR performance over an Rh electrocatalyst. After the addition of sulfate, the inert Rh nanoparticles exhibited superior NOR performance with a nitrate yield of 168.0 μmol g cat À 1 h À 1 . The 15 N isotope-labeling experiment confirmed the produced nitrate from nitrogen electrooxidation. A series of electrochemical in situ characterizations and theoretical calculation unveiled that sulfate promoted nitrogen adsorption and decreased the reaction energy barrier, and in situ formed sulfate radicals reduced the activation energy of the potential-determining step, thus accelerating NOR.