Highly Efficient Oxygen Evolution by a Thermocatalytic Process Cascaded Electrocatalysis Over Sulfur-Treated Fe-Based Metal-Organic-Frameworks

The oxygen evolution reaction (OER) is a bottleneck process for water splitting and finding highly efficient, durable, low-cost, and earth-abundant electrocatalysts is still a major challenge. Here a sulfur-treated Fe-based metal-organic-framework is reported as a promising electrocatalyst for the OER, which shows a low overpotential of 218 mV at the current density of 10 mA cm(-2) and exhibits a very low Tafel slope of 36.2 mV dec(-1) at room temperature. It can work on high current densities of 500 and 1000 mA cm(-2) at low overpotentials of 298 and 330 mV, respectively, by keeping 97% of its initial activity after 100 h. Notably, it can achieve 1000 mA cm(-2) at 296 mV with a good stability at 50 degrees C, fully fitting the requirements for large-scale industrial water electrolysis. The high catalytic performance can be attributed to the thermocatalytic processes of H+ capture by -SO3 groups from *OH or *OOH species, which cascades to the electrocatalytic pathway and then significantly reduces the OER overpotentials.