Understanding the Role of (W, Mo, Sb) Dopants in the Catalyst Evolution and Activity Enhancement of Co3O4 during Water Electrolysis via In Situ Spectroelectrochemical Techniques

Unlocking the potential of the hydrogen economy is dependent on achieving green hydrogen (H-2) production at competitive costs. Engineering highly active and durable catalysts for both oxygen and hydrogen evolution reactions (OER and HER) from earth-abundant elements is key to decreasing costs of electrolysis, a carbon-free route for H-2 production. Here, a scalable strategy to prepare doped cobalt oxide (Co3O4) electrocatalysts with ultralow loading, disclosing the role of tungsten (W), molybdenum (Mo), and antimony (Sb) dopants in enhancing OER/HER activity in alkaline conditions, is reported. In situ Raman and X-ray absorption spectroscopies, and electrochemical measurements demonstrate that the dopants do not alter the reaction mechanisms but increase the bulk conductivity and density of redox active sites. As a result, the W-doped Co3O4 electrode requires approximate to 390 and approximate to 560 mV overpotentials to reach +/- 10 and +/- 100 mA cm(-2) for OER and HER, respectively, over long-term electrolysis. Furthermore, optimal Mo-doping leads to the highest OER and HER activities of 8524 and 634 A g(-1) at overpotentials of 0.67 and 0.45 V, respectively. These novel insights provide directions for the effective engineering of Co3O4 as a low-cost material for green hydrogen electrocatalysis at large scales.

Automated summary

To decrease the cost of hydrogen production and unlock the potential of the hydrogen economy, highly active and durable catalysts for oxygen and hydrogen evolution reactions are needed. This study reports a scalable strategy to prepare doped cobalt oxide electrocatalysts that enhance the activity of these reactions in alkaline conditions. The doping elements increase the bulk conductivity and density of redox active sites without altering the reaction mechanisms. These findings provide insights for engineering Co3O4 as a low-cost material for green hydrogen electrocatalysis at large scales.