A Tandem Interfaced (Ni₃S₂‐MoS₂)@TiO₂ Composite Fabricated by Atomic Layer Deposition as Efficient HER Electrocatalyst

Abstract

Reported herein is a highly active and durable hydrogen evolution reaction (HER) electrocatalyst, which is constructed following a tandem interface strategy and functional in alkaline and even neutral medium (pH ≈ 7). The ternary composite material, consisting of conductive nickel foam (NF) substrate, Ni₃ S₂ -MoS₂ heterostructure, and TiO₂ coating, is synthesized by the hydrothermal method and atomic layer deposition (ALD) technique. Representative results include: (1) versatile characterizations confirm the proposed composite structure and strong electronic interactions among comprised sulfide and oxide species; (2) the material outperforms commercial Pt/C by recording an overpotential of 115 mV and a Tafel slope of 67 mV dec^-1 under neutral conditions. A long-term stability in alkaline electrolytes up to 200 h and impressive overall water splitting behavior (1.56 V @ 10 mA cm^-2 ) are documented; (3) implementation of ALD oxide tandem layer is crucial to realize the design concept with superior HER performance by modulating a variety of heterointerface and intermediates electronic structure.