Preparation of nickel–iron sulfide/oxide nanocomposites by biomineralization of sulfate-reducing bacterium for efficient oxygen evolution

Efficient electrolysis of water is critical for renewable energy technologies, and achieving this goal through low-cost, low-energy, and environmentally-friendly methods is imperative. The nanomaterials prepared by biomineralization have the characteristics of small particle size, strong stability, low cost, clean and environmental protection. This study utilized sulfate-reducing bacteria (SRB) to prepare oxygen evolution reaction (OER) catalysts based on the principles of biomineralization. To enhance its OER activity, three distinct doping methods were employed based on bacterial biomineralization products (BPs), and a possible biomineralization mechanism of SRB in the preparation of metal sulfides and iron compounds has been proposed. Our investigations demonstrated that Ni-doped biomineralized products hydrothermal treatment yielded an electrocatalyst having outstanding catalytic activity and performance, and it exhibited a small overpotential of 230 mV at a current density of 10 mA cm−2 as well as a Tafel slope down to 46 mV dec−1 in alkaline solution. This electrode material outperformed the commercial RuO2 electrocatalyst. The high catalytic activity of the prepared electrocatalyst is ascribed to the additional active sites introduced by the doping of Ni, facile electron transfer, enhanced conductivity, and wettability. Overall, the utilization of the biomineralization method for the catalytic material preparation can considerably facilitate the development of energy conversion and storage processes.