Boosting overall saline water splitting by constructing a strain‐engineered high‐entropy electrocatalyst

Abstract High‐entropy materials (HEMs), which are newly manufactured compounds that contain five or more metal cations, can be a platform with desired properties, including improved electrocatalytic performance owing to the inherent complexity. Here, a strain engineering methodology is proposed to design transition‐metal‐based HEM by Li manipulation (LiTM) with tunable lattice strain, thus tailoring the electronic structure and boosting electrocatalytic performance. As confirmed by the experiments and calculation results, tensile strain in the LiTM after Li manipulation can optimize the d ‐band center and increase the electrical conductivity. Accordingly, the as‐prepared LiTM‐25 demonstrates optimized oxygen evolution reaction and hydrogen evolution reaction activity in alkaline saline water, requiring ultralow overpotentials of 265 and 42 mV at 10 mA cm −2 , respectively. More strikingly, LiTM‐25 retains 94.6% activity after 80 h of a durability test when assembled as an anion‐exchange membrane water electrolyzer. Finally, in order to show the general efficacy of strain engineering, we incorporate Li into electrocatalysts with higher entropies as well.