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

Abstract

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.

Crystal Engineering Enables Cobalt-Based Metal–Organic Frameworks as High-Performance Electrocatalysts for H2O2 Production

“…Besides, the E d of ZnCo-ZIF-R3 is calculated to be 5.68 eV. The position of E d of the catalyst closely correlated with filling of the anti-bonding state near the Fermi level, which determines the binding strengths of the ORR intermediates. − It is generally accepted that the selectivity of 2e-ORR is associated with the d-band center of transition metal-based electrocatalysts. ,− An appropriate d-band center that allows the adsorption of oxygen-containing intermediates, neither too strong nor too weak, enables a high 2e-ORR selectivity. As shown in Figure d, the selectivity and the E d plot exhibits a volcano-type curve, where ZnCo-ZIF-C3 close to the peak of the volcano displays an intermediate E d of 4.63 eV.…”

“…This observation implies that the incorporation of Zn 2+ may reduce the electron cloud density around the cobalt center. 54,55 Compared with ZnCo-ZIF-C3, the binding energies of Co peaks in ZnCo-ZIF-R3 are almost unchanged, indicating the negligible impact of facet exposure on the electronic structure of Co 2+ . In addition, due to the fully occupied 3d 10 electronic configuration of Zn 2+ , the Zn 2p spectra of all samples (except ZIF-67) show similar peaks at 1021.95 and 1045.01 eV, attributing to Zn 2p 3/2 and 2p 1/2 , respectively (Figure S19).…”

In situ generated Cu–Co–Zn trimetallic sulfide nanoflowers on copper foam: a highly efficient OER electrocatalyst

“…Compared to CuCoZn–OH, the binding energy of the Zn 2p 3/2 peak (1022.0 eV) in CuCoZn–S-3 positively shifts by 0.2 eV. 47 This further indicates that there may be electron transfer between Cu, Zn and Co, with Cu and Zn providing electrons to Co and increasing the electron density at the active site, which would be beneficial for oxygen involved electrocatalysis. 48 In summary, the synergistic effect of trimetallic ions could tailor the electronic structure and will be beneficial for redox reactions.…”

Atomic-level orbital coupling in a tri-metal alloy site enables highly efficient reversible oxygen electrocatalysis

“…(1) The optimized electronic structure of the ternary alloy catalyst can bring about favorable interfacial charge-transfer, thus significantly reducing the energy barriers of various elementary reactions in the ORR/OER processes, and accelerating the kinetics of the reaction and improving the electrocatalytic efficiency. 79 (2) Ultra-small alloy particles allow more active sites to be exposed, which can promote the adsorption of reaction intermediates. 80 (3) The designed electrocatalyst presents a hollow characteristic, thus creating a richer electrochemical active area for the catalytic reaction and accelerating the transfer of mass/charges.…”