Thermo-selenizing to rationally tune surface composition and evolve structure of stainless steel to electrocatalytically boost oxygen evolution reaction

Oxygen evolution reaction (OER) is the bottleneck of the electrolytic water splitting process due to its high overpotential. There are great challenges to thermodynamically and kinetically enhance the electrocatalysis of OER. Here a thermo-selenization is presented to rationally tune the surface composition and largely evolve the structure of stainless steel (SS) for highly active sites toward OER. The modified SS remarkably delivers a high current density of 500 mA cm−2 with only 293 mV overpotential and high stability for 96 h continuous operation at a current density of 500 mA cm−2 with only ~10 mV increases of overpotential, which is superior to all reported SS based catalysts. The enhancement mechanism of the structural evolution toward OER is systematically investigated and supported by both experimental results and theoretical calculations. This work holds a great promise for a cost-effective, mass-production method to produce electrocatalysts toward OER, while offers fundamental insights to the enhancement mechanism of structure evolution for highly reconstructive reaction active sites in electrocatalysis.