Activate Fe₃S₄ Nanorods by Ni Doping for Efficient Dye-Sensitized Photocatalytic Hydrogen Production

Developing suitable catalysts capable of receiving injected electrons and possessing active sites for hydrogen evolution reaction (HER) is the key to building an efficient dye-sensitized system for hydrogen production. Fe₃S₄ is generally regarded as an inferior HER catalyst among the metal sulfide family, mainly due to its weak surface adsorption toward H atoms. In this work, we demonstrate a facile metal-organic framework-derived method to synthesize uniform Fe₃S₄ nanorods and active them for HER by Ni doping. Our experimental results and theoretical calculations reveal that Ni doping can greatly modify the electronic structure of Fe₃S₄ nanorods, improving their electron conductivity and optimizing their surface adsorption energy toward H atoms. Sensitized by a commercial organic dye (eosin-Y), 1%Ni-doped Fe₃S₄ nanorods display a high H₂ production rate of 3240 μmol g_cat^-1 h^-1 with an apparent quantum yield of 12% under 500 nm wavelength, which is significantly higher than that of pristine Fe₃S₄ and even higher than that of 1% Pt-deposited Fe₃S₄. The working mechanism of this dye-sensitized system is explored, and the effect of Ni-doping concentration has been studied. This work presents a facile strategy to synthesize metal-doped sulfide nanocatalysts with greatly enhanced activity toward photocatalytic H₂ production.