Zn substituted hydroxide/oxyhydroxide heterostructure activates proton conduction

The recent explorations on high performance aqueous electrode materials have witnessed an intensive interest in proton conduction. Transitional metal layer double hydroxides (LDHs) are considered as one potential candidate due to their rich detachable hydrogen atoms, however, proton conduction in LDH has rarely been reported. Herein, we construct a NiCo-hydroxide/oxyhydroxide heterostructure by Zn substitution. Experimental and theoretical results verify that Zn dopant can accelerate the partial transition of hydroxides to oxyhydroxides with the fixed interlayer distance, which just like locks, effectively restrains the interlayer expansion of neighboring LDH in electrochemical process. As a result, the OH- shuttle between interlayers is prohibited and the proton conduction is activated by a unique concerted mode between O-H bonds and water molecules in interlayer space, achieving a capacity rise of 160% and a superior cyclability with capacity retention of 120% after 37000 cycles at 30 A g-1. This success on proton conduction in LDH affords new insights into rational design and preparation of advanced aqueous electrode materials by activating proton conduction.