Sulfur-facilitated in situ deep reconstruction of transition metal molybdates toward superior electrocatalytic oxidation of alkaline seawater

Abstract

Inducing the rapid and deep self-reconstruction of anodes has the potential to achieve the desired structure for effective oxygen evolution reactions (OERs) in seawater, but it is challenging. Herein, sulfur-assisted structural reconstruction of transition metal molybdates was fabricated. Benefiting from the electronic escape effect that occurs due to metal–O/–S bonding orbitals in the pre-catalyst, deep electrochemical reconstruction to highly active S-doped oxyhydroxides was achieved via rational S–metal hybridization and phase transition in the pre-catalyst. Meanwhile, combining the theoretical calculations and spectroscopic tests, it was found that introducing S atoms into oxyhydroxides activated lattice oxygen atoms, thereby boosting the intrinsic OER activity following the lattice oxygen mechanism pathway. As tested, the final S-doped oxyhydroxide catalysts exhibited excellent electrocatalytic activity with an ultralow overpotential of 166 mV at 10 mA cm⁻² in alkaline seawater oxidation. This work showcased a feasible strategy of sulfur-assisted structural reconstruction to fabricate highly efficient and chemically stable materials for seawater splitting.