Novel fluorine-doped cobalt molybdate nanosheets with enriched oxygen-vacancies for improved oxygen evolution reaction activity

Herein, we have synthesized fluorine-doped cobalt molybdate (F-CoMoO4) nanosheet arrays on graphite felt (GF) to efficiently promote the oxygen evolution reaction (OER) kinetics. Experimental results show that F-CoMoO4 has two significant effects: 1) inducing rich oxygen vacancies, and 2) optimizing the electronic configuration of CoMoO4, which is beneficial for exposure of active sites. The as-obtained F-CoMoO4-x-2@GF electrocatalyst exhibits lower OER overpotential of 256 mV at 10 mA cm(-2) with a small Tafel slope of 64.4 mV dec(-1) in alkaline solution, resulting in a nearly 100 mV of OER catalytic activity enhancement compared with that of pure CoMoO4. DFT results reveal that the change of Mo 4d state reduces the band-gap and increases the electrical conductivity of CoMoO4, thus optimizing its intrinsic activity. The synthesis strategy used in this work may provide some ideas for enhancing the electrical conductivity of other transition metal oxides (TMOs).

Automated summary

In this study, fluorine-doped cobalt molybdate nanosheet arrays were synthesized on graphite felt to enhance the kinetics of the oxygen evolution reaction. The F-CoMoO4 electrocatalyst showed improved OER performance due to the induction of oxygen vacancies and optimization of the electronic configuration of CoMoO4. The DFT results revealed that the change in Mo 4d state led to a decrease in band-gap and an increase in electrical conductivity, thereby optimizing the intrinsic activity of CoMoO4. The synthesis strategy employed in this work may offer insights for enhancing the electrical conductivity of other transition metal oxides.