High-efficient Electrochemical Oxygen Evolution Reaction Catalyst Constructed by S-treated Two-dimension Prussian Blue Analogue

It is highly requisite for porous coordination polymers (PCPs) including metal-organic frameworks (MOFs) and Prussian blue analogues (PBAs) to remain their intrinsic characteristics in electrocatalysis, instead of using as precursors or templates for further totally conversion to other compounds via high-temperature calcination. Here, S-treated two-dimension (2D) CoFe bimetal PBA grown on carbon fiber paper (CFP) (named S-CoFe-PBA/CFP) is assembled and applied as high-efficient oxygen evolution reaction (OER) electrocatalyst in 1 M KOH. The resultant S-CoFe-PBA/CFP demonstrates a significantly improved OER catalytic activity, only overpotentials of 235 mV, 259 mV and 272 mV are needed to drive the current densities of 10 mA cm-2, 50 mA cm-2 and 100 mA cm-2, respectively, along with a super low Tafel slope of 35.2 mV dec-1. Even more noteworthy, current density of 90 mA cm-2 can be achieved when potential of 1.5 V vs. RHE is applied, which is 6.4 times higher than that of commercial Ir/C under the same environment. The outstanding electrocatalytic performance can be ascribed to two reasons caused by S-treated process. On one hand, H+ from intermediates of *OH and *OOH can be captured by -SOx distributed on the surface of catalyst, thus accelerate the breaking of O-H; On the other hand, partial phase transformation of CoFe-PBA leads to in-situ formation of amorphous CoSx nanogauze on its surface, the resultant electronic interaction between two phases contribute much to improvement of charge transfer and adsorption for OER intermediates. This work provides a new avenue for the design of high-efficient PCPs-based OER electrocatalysts.