Boosting Efficient and Sustainable Alkaline Water Oxidation on a W-CoOOH-TT Pair-Sites Catalyst Synthesized via Topochemical Transformation

The development of facile methods for constructing highly active, cost-effective catalysts that meet ampere-level current density and durability requirements for an oxygen evolution reaction is crucial. Herein, a general topochemical transformation strategy is posited: M-Co9S8 single-atom catalysts (SACs) are directly converted into M-CoOOH-TT (M = W, Mo, Mn, V) pair-sites catalysts under the role of incorporating of atomically dispersed high-valence metals modulators through potential cycling. Furthermore, in situ X-ray absorption fine structure spectroscopy is used to track the dynamic topochemical transformation process at the atomic level. The W-Co9S8 breaks through the low overpotential of 160 mV at 10 mA cm-2. A series of pair-site catalysts exhibit a large current density of approaching 1760 mA cm-2 at 1.68 V vs reversible hydrogen electrode (RHE) in alkaline water oxidation and achieve a approximate to 240-fold enhancement in the normalized intrinsic activity compare to that reported CoOOH, and sustainable stability of 1000 h. Moreover, the OO bond formation is confirmed via a two-site mechanism, supported by in situ synchrotron radiation infrared and density functional theory (DFT) simulations, which breaks the limit of adsorption-energy scaling relationship on conventional single-site. A general potential cycling topochemical transformation ("PCTT") strategy is used to convert M-Co9S8 single-atom catalysts (SACs) into M-CoOOH-TT pair sites (M = W, Mo, Mn, V) under the modulation of atomically dispersed high-valence metals; this TT process can be confirmed by in situXAFS. The prepared tungsten-based pair-sites catalyst makes a breakthrough of 3000 mA cm-2 high current density and 1000 h long-term stability. Furthermore, the OO bond formation process on two Co sites is well confirmed by in situ synchrotron radiation infrared and density functional theory, which breaks the limit of the adsorption-energy scaling relationship on conventional single-sites.image