Improved OER electrocatalytic performance of Co-MOF by forming heterojunction with lower-conductivityWO3 nanorods or Cr2O3 nanoparticles

For the Metal-organic framework materials (MOFs), the poor conductivity limits its direct use as electrocatalysts. A kind of amazing WO3 NRs@Co-MOF composite catalyst are constructed by anchoring Co-MOF nanocrystals on the surface of lower-conductivity WO3 nanorods (Its charge-transfer impedance value is relatively lower than the Co-MOF). The two-phase interface of WO3 NRs and Co-MOF with chemical bonds and oxygen vacancies favors increasing the active sites. As a result, the excellent oxygen evolution reaction (OER) electrocatalytic activity of WO3 NRs@Co-MOF and the WO3 NRs@Co-MOF/NF(with nickel foam as substrate) are demonstrated. Density functional theory calculations have further validated the lowest free energy levels of intermediates for WO3 NRs@Co-MOF induce the fastest OER reaction. The composite electrode of Cr2O3 nanoparticles and Co-MOF supported on nickel foam (Cr2O3 NPs@Co-MOF/NF) also has similar interfacial structure and electrocatalytic activity as that of WO3 NRs@Co-MOF/NF composites. The research about this kind of lower-conductivity oxides based composite catalysts broadens the preparation path of MOF composite catalysts and reduces the cost, which is great significant to the research and application of high efficiency OER electrocatalysts.