Formic acid is considered one of the most economically viable products for electrocatalytic CO₂ reduction reaction (CO₂RR). However, developing highly active and selective electrocatalysts for effective CO₂ conversion remains a grand challenge. Herein, we report that structural modulation of the bismuth oxide nanosheet via Zn²⁺ cooperation has a profound positive effect on exposure of the active plane, thereby contributing to high electrocatalytic CO₂RR performance. The obtained Zn-Bi₂O₃ catalyst demonstrates superior selectivity towards formate generation in a wide potential range; a high Faradaic efficiency of 95% and a desirable partial current density of around 20 mA·cm⁻² are obtained at −0.9 V (vs. reversible hydrogen electrode (RHE)). As proposed by density functional theory calculations, Zn substitution is the most energetically feasible for forming and stabilizing the key OCHO* intermediate among the used metal ions. Moreover, the more negative adsorption energy of OCHO* and the relatively low energy barrier for the desorption of HCOOH* are responsible for the enhanced activity and selectivity.

Industrial hydrogen generation through water splitting, powered by renewable energy such as solar, wind and marine, paves a potential way for energy and environment sustainability. However, state-of-the-art electrolysis using high purity water as hydrogen source at an industrial level would bring about crisis of freshwater resource. Seawater splitting provides a practical path to solve potable water shortage, but still faces great challenges for large-scale industrial operation. Here we summarize recent developments in seawater splitting, covering general mechanisms, design criteria for electrodes, and industrial electrolyzer for direct seawater splitting. Multi-objective optimization methods to address the key challenges of active sites, reaction selectivity, corrosion resistance, and mass transfer ability will be discussed. The recent development in seawater electrolyzer and acquaint efficient strategies to design direct devices for long-time operation are also highlighted. Finally, we provide our own perspective to future opportunities and challenges towards direct seawater electrolysis.