Teng Yang^‡, Honghao Lv^‡, Qinghao Quan, Xiaolei Li, Huasen Lu, Xuejing Cui, Guangbo Liu*^,, and Luhua Jiang*

College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China

^‡Those authors contributed equally to this work.

ABSTRACT: Electronic structure modulation is an effective strategy for electrocatalysts to boost their hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities in water splitting. Here, a rational design of rare earth element Er-doped MoO₂ (Er-MoO₂) with modulated electronic structure is reported, leading to boosted water splitting activity in both alkaline and seawater electrolyte. Experimental results manifest that the optimized Er-MoO₂ requires overpotentials of only 94/221 mV and 173/312 mV to deliver the 10 mA cm^-2 for HER/OER in alkaline and seawater electrolyte, respectively. As bifunctional electrocatalysts for overall water splitting, the Er-MoO₂ requires a cell voltage of only 1.52 and 1.67 V to gain 10 mA cm^-2 in alkaline and seawater electrolyte, respectively. Moreover, a Mg/seawater battery coupled with the Er-MoO₂ cathode achieving a maximum power density of 8.17 mW cm^-2, combining with an excellent discharging stability for at least 24 h. This work provides a facile strategy toward the design of efficient non-noble metal catalysts for overall water/seawater splitting and Mg/seawater battery.

https://doi.org/10.1016/j.apsusc.2023.156360