CdS@Ni3S2 core–shell nanorod arrays on nickel foam: a multifunctional catalyst for efficient electrochemical catalytic, photoelectrochemical and photocatalytic H2 production reaction

Producing green hydrogen fuel from water is one of the most promising strategies for sustainable and clean energy supply in the future. Seeking for highly efficient, noble-metal-free and stable catalysts for typical electrochemical catalytic (EC), photoelectrochemical (PEC) and photocatalytic (PC) hydrogen production has attracted much attention. In this work, for the first time, we rationally designed and fabricated an innovative class of CdS@Ni3S2 core–shell nanorod arrays (CSNS) on Ni foam. Thanks to the synergistic effect and catalytic role transformation between CdS nanorods and Ni3S2 nanosheets, CSNS was determined to be a new type of multifunctional noble-metal-free catalyst, which exhibited highly stable and efficient H2 production properties in EC, PEC and PC hydrogen production systems. Specifically, with an optimal Ni3S2 shell thickness, CSNS achieved its highest PEC activity with an applied bias photon-to-current conversion efficiency (ABPE) of 7.9% and an extremely high H2 production rate of 112.5 μmol cm−2 min−1. Moreover, a series of inconsistent catalytic behaviors were found during the EC, PEC and PC hydrogen production procedures. By establishing three corresponding charge separation and transfer models, the underlying catalytic mechanisms and the dominant role transformations between CdS and Ni3S2 in these three catalytic systems were systematically investigated. This study provides a new strategy and guidelines for searching for suitable photocatalysts/electrocatalysts and core–shell multifunctional catalysts which can be used in an optional H2 production system.