Trimetallic Sulfide Hollow Superstructures with Engineered d-Band Center for Oxygen Reduction to Hydrogen Peroxide in Alkaline Solution.

High-performance transition metal chalcogenides (TMCs) as electrocatalysts for two-electron oxygen reduction reaction (2e-ORR) in alkaline medium are promising for hydrogen peroxide (H 2 O 2 ) production, but their synthesis remains challenging. In this work, a titanium-doped zinc-cobalt sulfide hollow superstructure (Ti-ZnCoS HSS) is rationally designed as an efficient electrocatalyst for H 2 O 2 electrosynthesis. Synthesized by using hybrid metal-organic frameworks (MOFs) as precursors after sulfidation treatment, the resultant Ti-ZnCoS HSS exhibits a hollow-on-hollow superstructure with small nanocages assembled around a large cake-like cavity. Both experimental and simulation results demonstrate that the polymetallic composition tailors the d-band center and binding energy with oxygen species. Moreover, the hollow superstructure provides abundant active sites and promotes mass and electron transfer. The synergistic d-band center and superstructure engineering at both atomic and nanoscale levels lead to the remarkable 2e-ORR performance of Ti-ZnCoS HSS with a high selectivity of 98%, activity (potential at 1 mA cm -2 of 0.774 V vs reversible hydrogen electrode (RHE)), a H 2 O 2 production rate of 675 mmol h -1 g cat -1 , and long-term stability in alkaline condition, among the best 2e-ORR electrocatalysts reported to date. This strategy paves the way toward the rational design of polymetallic TMCs as advanced 2e-ORR catalysts.