Tailored on-surface fabrication of mesoporous metallic composites by direct pyrolysis of metal ion-accumulated micellar films for enhanced electrocatalytic water splitting

Abstract

Amphiphilic block copolymers have been ubiquitously utilized as templates for the diverse fabrication of mesoporous films with tunable structure and constitution. However, the formation process normally relies on a delicate sol–gel process as well as a fine control of the cooperation between the soft templates and precursors. Herein, we develop a block copolymer micellar film system to direct the formation of highly tailored mesoporous metal/metal oxide composites in the absence of a sol–gel process. The poly(2-vinylpyridine) corona in the micellar film provides a mild and dynamic coordination platform for the fast capture and abundant accumulation of various metal ions (e.g. Ru³⁺, Pt²⁺, Pd²⁺, Ir³⁺, and Fe³⁺). Meanwhile, solvent treatment further triggers a sphere-to-cylinder phase transition of the metal ion-accumulated micellar film. Upon one-step pyrolysis, the metal ion-accumulated micellar films immediately convert into mesoporous composite films with tunable constitution and pore structure on desired substrates. Benefiting from the open channels and synergistic effects of multiple components, the mesoporous N–Ru/RuO₂/NiO film with cylindrical cavities reveals a low potential of 1.53 V at 200 mA cm⁻² for water splitting. The assembled anion exchange membrane electrolyzer can operate stably at a high current density of 2.0 A cm⁻² at 1.77 V for over 200 h.