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

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. Strain engineering of high-entropy materials has been carried out with the involvement of Li. The presence of lattice strain leads to an upward shift of the transition-metal d-band centers, optimizing the free energy of the absorbate while increasing the electronic conductivity, which in turn greatly improves the electrocatalytic performance. As-prepared high-entropy electrocatalysts show excellent water-splitting stability in alkaline saline water. image An innovative design and fabrication method for high-entropy electrocatalysts with strain strategies is reported. Optimized electrocatalysts show ultralow oxygen evolution reaction (265 mV) and hydrogen evolution reaction (42 mV) overpotentials at 10 mV cm-2 in alkaline saline water. The universal enhanced catalytic activity of high-entropy electrocatalysts is verified by the addition of metal species. It is proved that the presence of lattice strain optimizes the d-band center of the active site.