Electrocatalytic NO reduction reaction to generate NH 3 under ambient conditions offers an attractive alternative to the energy-extensive Haber-Bosch route; however, the challenge still lies in the development of cost-effective and high-performance electrocatalysts. Herein, nanoporous VN film is first designed as a highly selective and stable electrocatalyst for catalyzing reduction of NO to NH 3 with a maximal Faradaic efficiency of 85% and a peak yield rate of 1.05 × 10 -7 mol•cm -2 •s -1 (corresponding to 5,140.8 g•h -1 •mg cat.-1 ) at -0.6 V vs. reversible hydrogen electrode in acid medium. Meanwhile, this catalyst maintains an excellent activity with negligible current density and NH 3 yield rate decays over 40 h. Moreover, as a proof-of-concept of Zn-NO battery, it delivers a high power density of 2.0 mW•cm -2 and a large NH 3 yield rate of 0.22 × 10 -7 mol•cm -2 •s -1 (corresponding to 1,077.1 g•h -1 •mg cat.-1 ), both of which are comparable to the best-reported results. Theoretical analyses confirm that the VN surface favors the activation and hydrogenation of NO by suppressing the hydrogen evolution. This work highlights that the electrochemical NO reduction is an eco-friendly and energy-efficient strategy to produce NH 3 .

No abstract

Energy crisis and environmental pollution trigger the development of efficient and robust electrochemical energy conversion and storage technologies. [1-3] The electrocatalytic reactions, such as hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR), undoubtedly play key roles in developing renewable energy conversion devices, Development of cost-effective, active trifunctional catalysts for acidic oxygen reduction (ORR) as well as hydrogen and oxygen evolution reactions (HER and OER, respectively) is highly desirable, albeit challenging. Herein, singleatomic Ru sites anchored onto Ti 3 C 2 T x MXene nanosheets are first reported to serve as trifunctional electrocatalysts for simultaneously catalyzing acidic HER, OER, and ORR. A half-wave potential of 0.80 V for ORR and small overpotentials of 290 and 70 mV for OER and HER, respectively, at 10 mA cm −2 are achieved. Hence, a low cell voltage of 1.56 V is required for the acidic overall water splitting. The maximum power density of an H 2-O 2 fuel cell using the as-prepared catalyst can reach as high as 941 mW cm −2. Theoretical calculations reveal that isolated Ru-O 2 sites can effectively optimize the adsorption of reactants/intermediates and lower the energy barriers for the potentialdetermining steps, thereby accelerating the HER, ORR, and OER kinetics.

No abstract

N‐coordinated transition‐metal materials are crucial alternatives to design cost‐effective, efficient, and highly durable catalysts for electrocatalytic oxygen reduction reaction. Herein, the synthesis of uniformly distributed Cu−Zn clusters on porous N‐doped carbon, which are accompanied by Cu/Zn‐Nx single sites, is demonstrated. X‐ray absorption fine structure tests reveal the co‐existence of M−N (M = Cu or Zn) and M−M bonds in the catalyst. The catalyst shows excellent oxygen reduction reaction (ORR) performance in an alkaline medium with a positive half‐wave potential of 0.884 V, a superior kinetic current density of 36.42 mA cm−2 at 0.85 V, and a Tafel slope of 45 mV dec−1, all of which are among the best‐reported results. Furthermore, when employed as an air cathode in Zn‐Air battery, it reveals a high open‐cycle potential of 1.444 V and a peak power density of 164.3 mW cm−2. Comprehensive experiments and theoretical calculations approved that the high activity of the catalyst can be attributed to the collaboration of the Cu/Zn‐N4 sites with CuZn moieties on N‐doped carbons.