Synergizing ruthenium oxide with bimetallic Co2CrO4 for highly efficient oxygen evolution reaction.

Designing efficient and stable oxygen evolution reaction (OER) catalyst is the basis for the development of sustainable electrolytic water energy techniques. In this work, we presented a heterogeneous-structured electrocatalyst composed of bimetallic oxides-modified RuO2 nanosheets supported on nikel foam (Co2CrO4/RuO2) using a hybrid hydrothermal, ion-exchange and calcination method. The unique synergy and interfacial coupling between Co2CrO4/RuO2 heterostructures are favorable for optimizing the electronic configuration at this interface and strengthening the charge transport capacity, thus strengthening the catalytic activity of the Co2CrO4/RuO2 catalyst. The experimental data demonstrate that Cr leaching facilitates the rapid reconstruction of the catalyst into oxyhydroxides (CoOOH), which are acknowledged to be the real active species of OER. Theoretical calculations show that the Co2CrO4/RuO2 heterostructure increases the density state at the Fermi energy level and lowers the d-band center, thereby strengthening the catalytic activity. The synthesized Co2CrO4/RuO2 catalyst exhibited OER performance with an overpotential of 209 mV at 10 mA cm-2 and displayed a low Tafel slope of 78.2 mV dec-1, which outperforms most reported advanced alkaline OER catalysts. This work contributes to a new tactic for the design and development of ruthenium oxide/bimetallic oxides electrocatalysts.

Synergistically coupled CoMo/Fe2O3 electrocatalyst for highly efficient and stable overall water splitting.

Constructing bifunctional non-precious metal electrocatalysts with advanced industrial value and excellent electrocatalytic performance to achieve efficient overall water splitting is important but difficult. Herein, a heterogeneous electrocatalyst comprising of CoMo alloys anchored Fe2O3 nanosheets was prepared by hydrothermal and electrodeposition methods. The strongly coupled interfaces between the CoMo alloys and Fe2O3 nanosheets promote charge redistribution, which could improve electron transfer efficiency and accelerate reaction kinetics, potentially optimizing reactant adsorption energy. Further density functional theory (DFT) calculations reveal that the construction of CoMo/Fe2O3/NF heterostructured catalyst facilitates to promote interfacial charge redistribution and enhance charge transfer capacity, thus boosting the catalytic performance. Benefiting from this, the optimal CoMo/Fe2O3/NF heterostructure demonstrates a minimal overpotential of 71 mV at 10 mA cm-2 for the HER and 266 mV at 50 mA cm-2 for the OER. Remarkably, the catalyst served as a bifunctional electrode for water splitting, resulting in a cell voltage down to 1.5 V at a current density of 10 mA cm-2. This research provides an effective way for the construction of non-precious iron oxides-based bifunctional electrocatalysts using alloy/metal oxide interfacial engineering strategy.