Hierarchically porous Ni foam-supported Co and Sn doped Ni3S2 nanosheets for oxygen evolution reaction electrocatalysts

To enter the era of a clean and sustainable hydrogen economy, it is crucial to first discover non-noble metal electrocatalysts that can be used for oxygen evolution reactions (OER) of water electrolyzers. Herein, we demonstrate highly active and durable Co- and Sn-co-doped Ni3S2 catalysts supported on Ni foam (CoSn-Ni3S2@NF) for the OER in alkaline media. Benefiting from the hierarchically porous nanosheet morphology and synergistic strong electron interaction among Co, Sn, and Ni ions, the CoSn-Ni3S2@NF achieves outstanding OER activity in 1 M KOH with a low overpotential of 321 mV at a current density of 0.2 A cm(-2). Furthermore, the CoSn-Ni3S2@NF alkaline water electrolysis cell shows a significantly high current density of 1.367 A cm(-2) at a cell voltage of 2.0 V under 80 degrees C and 30 wt% KOH condition using a nickel-iron layered double hydroxide for the hydrogen evolution reaction and a Zirfon PERL separator (500 mu m). Based on the defect formation energy and electronic structure obtained using density functional theory calculation, the enhanced intrinsic activity of CoSn-Ni3S2@NF can be attributed to the Co and Sn dopants with S vacancies, which increase activation sites (and free electrons) and favorably modify the Ni 3d-band center to be closer to the Fermi level. This work not only demonstrates a highly electrocatalytic active OER catalyst for water electrolyzers, but also provides a new design principle that can be used for high performance materials by tailoring the electronic structure of transition and post transition metal ions.

Automated summary

In order to achieve a clean and sustainable hydrogen economy, researchers have developed a non-noble metal electrocatalyst, CoSn-Ni3S2@NF, for the oxygen evolution reaction in water electrolyzers. This catalyst exhibits outstanding activity and durability due to its hierarchically porous nanosheet morphology and the synergistic electron interaction among Co, Sn, and Ni ions. The enhanced intrinsic activity of CoSn-Ni3S2@NF is attributed to the presence of Co and Sn dopants with S vacancies, which increase activation sites and modify the electronic structure.