W-induced formation of Ir-WOx(W) flattened nanoparticles anchored on TiN support for acidic oxygen evolution

W induces flattened Ir-WO x (W) nanoparticles for high Ir utilization. • Alloy-heterojunctional composite interfaces tune Ir electronic structure for OER. • W optimizes OER intermediates and restrains Ir agglomeration to amplify Ir catalytic activity. • TiN-supported Ir-WO x flattened nanoparticles synthesized through a green approach. • Enhanced acidic OER activity vs commercial IrO 2 . Reducing the Ir loading in anode reaction catalysts is crucial for the scalable commercialization of proton exchange membrane (PEM) water electrolysis. Herein, W-induced formation of Ir-WO x (W) flattened nanoparticles with alloy-heterojunctional composite structure anchored on TiN support (Ir-WO x (W)/TiN) catalyst via a spray drying and heat treatment process is designed. For Ir-WO x (W)/TiN catalyst, TiN serves as the catalyst support, effectively achieving high dispersion of Ir as nanostructure on the support and enhancing the atomic utilization of Ir. W induces the formation of Ir-WO x (W) flattened nanoparticles to further improve atomic utilization efficiency of Ir and optimize its surface electronic structure during the oxygen evolution reaction (OER). Meanwhile, alloy-heterojunctional composite interfaces formed between Ir-WO x (W) and Ir-Ti can further optimize the adsorption/desorption capability of Ir toward oxygen-intermediates, lowering the energy barrier of the rate-determining step in the OER and enhancing the overall activity of catalyst, which is confirmed by a DFT calculation. The Ir-WO x (W)/TiN catalytic material demonstrates excellent OER performance, achieving overpotential of 221 mV and 296 mV at current densities of 10 mA·cm −2 and 50 mA·cm −2 in 0.5 M H 2 SO 4 solution, respectively, with a low Ir loading of 0.15 mg·cm −2 . Furthermore, this work demonstrates a green and scalable synthetic route without wastewater generation.