Built-in electric field construction and lattice oxygen activation for boosting alkaline electrochemical water/seawater oxidation

Oxygen evolution reaction (OER) remains a bottleneck for hydrogen production by water-alkali electrolysis at high industrial current density, but the structure-activity relationship of the catalyst and the underlying catalytic mechanism are still debated, which always limits the design of efficient catalysts. Herein, we report a proof-ofconcept hierarchical hydroxide/sulfide (NiFe LDH/Ni3S2) heterostructure as model catalyst to simultaneously adjust the electronic states and activate lattice oxygen. As-activated NiFe LDH/Ni3S2 electrode displays promising OER capability with an ultra-low overpotential of 295 mV at the industrial current density of 500 mA center dot cm- 2. The interface-induced built-in electric field effect promotes the asymmetric charge distribution on both sides. Insitu/ex-situ characterization demonstrates the adjusted intermediates adsorption/desorption and accelerated OER kinetics due to rapid electron transfer. A series of electrochemical probe experiments reveal that the OER mechanism of NiFe LDH/Ni3S2 follows the lattice oxygen mechanism. Especially, the super-strong wettability electrode design and structural advantages effectively enhance mass transfer and promote O2 desorption in alkaline water/seawater splitting systems. This work provides an avenue to break through OER limitations for efficient electrocatalytic water oxidation.