The electrochemical reduction of CO2 to produce carbon-based fuels and chemicals possesses huge potentials to alleviate current environmental problems. However, it is confronted by great challenges in the design of active electrocatalysts with low overpotentials and high product selectivity. Here we report the atomic tuning of a single-Fe-atom catalyst with phosphorus (Fe–N/P–C) on commercial carbon black as a robust electrocatalyst for CO2 reduction. The Fe–N/P–C catalyst exhibits impressive performance in the electrochemical reduction of CO2 to CO, with a high Faradaic efficiency of 98% and a high mass-normalized turnover frequency of 508.8 h–1 at a low overpotential of 0.34 V. On the basis of ex-situ X-ray absorption spectroscopy measurements and DFT calculations, we reveal that the tuning of P in single-Fe-atom catalysts reduces the oxidation state of the Fe center and decreases the free-energy barrier of *CO intermediate formation, consequently maintaining the electrocatalytic activity and stability of single-Fe-atom catalysts.

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The electrochemical CO2 reduction reaction (CO2RR) is a promising strategy to alleviate excessive CO2 levels in the atmosphere and produce value-added feedstocks and fuels. However, the synthesis of high-efficiency and robust electrocatalysts remains a great challenge. This work reports the green preparation of surface-oxygen-rich carbon-nanorod-supported bismuth nanoparticles (SOR Bi@C NPs) for an efficient CO2RR toward formate. The resultant SOR Bi@C NPs catalyst displays a Faradaic efficiency of more than 91% for formate generation over a wide potential range of 440 mV. Ex situ XPS and XANES and in situ Raman spectroscopy demonstrate that the Bi-O/Bi (110) structure in the pristine SOR Bi@C NPs can remain stable during the CO2RR process. DFT calculations reveal that the Bi-O/Bi (110) structure can facilitate the formation of the *OCHO intermediate. This work provides an approach to the development of high-efficiency Bi-based catalysts for the CO2RR and offers a unique insight into the exploration of advanced electrocatalysts.

Electrochemical reduction of CO 2 to produce fuels and chemicals is one of the most valuable approaches to achieve a carbon-neutral cycle. Recently, a diversity of catalysts have been developed to improve their intrinsic activity and efficiency. However, the dynamic evolution process and the in situ construction behavior of electrocatalysts under the working conditions are typically ignored. Here, we fully reveal the dynamic reduction process and phase transformation of a copper tin sulfide catalyst reconstructed by in situ reduction of the precatalyst Cu 2 SnS 3 and CuS during electrochemical CO 2 reduction. Furthermore, the reconstructed catalyst reaches an outstanding electrochemical CO 2 -to-formate conversion with a high Faradaic efficiency of 96.4% at an impressive production rate of 124889.9 μmol mg −1 h −1 under a partial current density of −241 mA cm −2 (−669.4 A g −1 ) in a flow-cell reactor. Theoretical calculations further demonstrate the strong charge interaction between the adsorbate and substrate to accelerate the charge transfer and decrease the formation energies of OCHO* and HCOOH* intermediates in the pathway of CO 2 to HCOOH, resulting in high selectivity for formate on the surface of the copper tin sulfide catalyst. This work paves the way for revealing the in situ dynamic process of the reconstructed catalyst and designing optimal catalysts with high catalytic activity and selectivity.

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Large-scale energy production and storage applications call for the development of advanced electrochemical systems including rechargeable batteries and water splitters, whose performances are largely determined by their active materials. In this work, we demonstrate an integrated hydrogen gas production and energy storage system by implementing a self-powered water splitter with hydrogen gas batteries. Such an integrated system is achieved by the application of a multifunctional nickel–cobalt phosphate (NCP) via a facile electrodeposition method. Due to the synergistic effect between Ni, Co, and phosphate ions, the NCP shows better redox reactions for energy storage and higher electrochemical activity than its hydroxide counterpart. When acting as a cathode, the NCP exhibits a high specific capacity of 278 mAh g–1 at 1.52 C, impressive rate performance, and outstanding cycling stability for over 12,000 cycles. Therefore, the assembled NCP–H2 battery based on the NCP cathode and H2 anode shows outstanding rate performance and long-term stability. Furthermore, an integrated water splitter using the NCP as bifunctional catalysts for hydrogen and oxygen evolution reactions is self-powered by the NCP–H2 battery, showing multifunctional properties of our NCP for potential energy production and storage applications.