Nano-Micro Letters | 2019
High-Index-Faceted Ni3S2 Branch Arrays as Bifunctional Electrocatalysts for Efficient Water Splitting
Abstract
HighlightsTiO2@Ni3S2 core/branch arrays are constructed via a low-temperature sulfurization.Highly active {$$\\bar{2}10$$2¯10} high-index facet of Ni3S2 is exposed for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER).Remarkable bifunctional electrocatalytic activity is observed for both HER and OER.AbstractFor efficient electrolysis of water for hydrogen generation or other value-added chemicals, it is highly relevant to develop low-temperature synthesis of low-cost and high-efficiency metal sulfide electrocatalysts on a large scale. Herein, we construct a new core–branch array and binder-free electrode by growing Ni3S2 nanoflake branches on an atomic-layer-deposited (ALD) TiO2 skeleton. Through induced growth on the ALD-TiO2 backbone, cross-linked Ni3S2 nanoflake branches with exposed {$$\\bar{2}10$$2¯10} high-index facets are uniformly anchored to the preformed TiO2 core forming an integrated electrocatalyst. Such a core–branch array structure possesses large active surface area, uniform porous structure, and rich active sites of the exposed {$$\\bar{2}10$$2¯10} high-index facet in the Ni3S2 nanoflake. Accordingly, the TiO2@Ni3S2 core/branch arrays exhibit remarkable electrocatalytic activities in an alkaline medium, with lower overpotentials for both oxygen evolution reaction (220\xa0mV at 10\xa0mA\xa0cm−2) and hydrogen evolution reaction (112\xa0mV at 10\xa0mA\xa0cm−2), which are better than those of other Ni3S2 counterparts. Stable overall water splitting based on this bifunctional electrolyzer is also demonstrated.