Potentiostatically pretreated electrochromic WO ₃ films (right) show much better durability under very harsh cycling conditions than untreated films (left).

The oxygen evolution reaction (OER) is the efficiency-determining half-reaction process of high-demand, electricity-driven water splitting due to its sluggish four-electron transfer reaction. Tremendous effects on developing OER catalysts with high activity and strong acid-tolerance at high oxidation potentials have been made for proton-conducting polymer electrolyte membrane water electrolysis (PEMWE), which is one of the most promising future hydrogen-fuel-generating technologies. This review presents recent progress in understanding OER mechanisms in PEMWE, including the adsorbate evolution mechanism (AEM) and the lattice-oxygen-mediated mechanism (LOM). We further summarize the latest strategies to improve catalytic performance, such as surface/interface modification, catalytic site coordination construction, and electronic structure regulation of catalytic centers. Finally, challenges and prospective solutions for improving OER performance are proposed.

The high-performance bi-functional electrochromic supercapacitor constitutes the critical technology for intelligent energy conversion and storage. Facilitating ion/electron transport and intercalation/deintercalation by rational design of the highly porous structure with a large specific surface area is one of the most effective strategies to promote its electrochemical redox reaction. However, difficult issues such as unsatisfactory energy storage due to simple porous structures and severe performance degradation during long-term electrochemical cycles still remain. Inspired by the natural geotexture of forests, a novel Ni/Co-based layered double hydroxide (Ni/Co-LDH) derived from the metal–organic framework grown on ZnO nanotubes on transparent conducting substrates with diverse porous structures is proposed to simulate the “rock-soil-tree-leaf” system. Excellent transmittance modulation, switching speed, specific capacity and durability are realized due to the large specific surface area of the three-dimensional network structured ZnO@Ni/Co-LDH, enhanced OH⁻ capture ability of ZnO, improved electrochemical activity by Ni/Co incorporation and its mixed charge storage behavior. Remarkable electrochromic and energy storage performance of the ZnO@Ni/Co-LDH device is also demonstrated. It serves as an intelligent energy conversion and storage platform to realize automatic optical switching by solar energy collection and charge storage/release. The new insights will pave the way for next-generation intelligent technologies towards a sustainable and liveable future life.