Accelerated oxygen evolution kinetics on nickel–iron diselenide nanotubes by modulating electronic structure

Development of cost-effective, highly active and durable electrocatalysts is highly demanded for oxygen evolution reaction (OER), which is an indispensable process involved in water splitting cells and metal-air batteries. Here, we accelerate the sluggish OER kinetics by controlling the morphology and engineering electronic structure of Fe _x Ni _1-x Se ₂ catalysts. Fe _x Ni _1-x Se ₂ nanotubes with tunable stoichiometry were fabricated through the removal of sacrificial templates (Cu ₂ O nanowires) and subsequent low-temperature selenization process. By precise tuning of Fe doping amount in Fe _x Ni _1-x Se ₂ nanotubes, the optimized Fe _0.125 Ni _0.875 Se ₂ nanotubes show a low overpotential of 253 mV at a current density of 10 mA cm ⁻² , a small Tafel slope of 49 mV dec ⁻¹ , and superior durability. By combining analysis of the experimental results with density-functional-theory (DFT) simulations, we reveal that the in-situ formed amorphous hydroxyl group layers on the surface of Fe _0.125 Ni0 _.875 Se ₂ (Fe _0.125 Ni _0.875 Se ₂ –OH) enable highly efficient oxygen evolution catalysis. The Fe dopant can achieve a near-optimal adsorption energy for OER intermediates (OH* O* and OOH*) on the oxidized surface of Fe _0.125 Ni _0.875 Se ₂ –OH, which is responsible to the enhanced OER performance of Fe _0.125 Ni _0.875 Se ₂ . This work paves a new way for exploring low cost and highly active OER electrocatalysts based on ternary metal selenides with hollow structure.