Synergistic Coupling of SnS2 Nanosheet Arrays with Ni/Fe Dual Metal and Ru Nanodots via a Cation Exchange Strategy for Overall Water Splitting

The application of tin disulfide (SnS2) in electrochemical water splitting remains a challenging issue on account of its unsatisfactory intrinsic electron conductivity and electrocatalytic activity. In this work, the vertically aligned SnS2 nanosheet arrays with open porous mass transfer pathways are synthesized, while the rational surface modification of highly electrocatalytic active heteroatoms (Ni/Fe or Ru) onto the SnS2 surface is achieved by a cation exchange strategy. The as-prepared Ni/Fe dual-metal-doped SnS2 on carbon cloth (NiFe-SnS2/CC) with abundant S vacancies and Ru nanodots-modified SnS2 (Ru-SnS2/CC) with SnS2/SnS heterostructures can effectively enhance the electron conductivity and the electrocatalytic activity. Benefiting from the plenty of metal heteroatoms and defects, the onset overpotential of the NiFe-SnS2/CC composite is only 251 mV for oxygen evolution reaction, while the value of Ru-SnS2/CC is 81 mV for hydrogen evolution reaction, along with robust long-term durability. Moreover, the assembled NiFe-SnS2/CC-3||Ru-SnS2/CC-10 electrolyzer device can attain a low cell voltage of 1.576 V at 10 mA cm–2. This project provides the methodology for promoting the low electrocatalytic species for high-performance energy conversion as well as a rational surface modification strategy through a cation exchange reaction.