Heterojunction of CoMoO4/SrTiO3 as efficient electrocatalysts for hydrogen evolution reaction and oxygen evolution reaction in alkaline media
M. A. Sardar, Muhammad Aamir, Sher Muhammad, It Ee Lee, Qamar Wali, Muhammad Ejaz Khan, Md. Akhtaruzzaman, Md. Shahiduzzaman, Javeed Akhtar, Jean‐Michel Nunzi
Abstract
• A p–n heterojunction was engineered between CoMoO₄ (CMO) and SrTiO₃ (STO) to modulate electronic states for enhanced electrocatalysis. • The 60%CMO-STO heterojunction exhibited superior bifunctional activity with low overpotentials of 102 mV (HER) and 280 mV (OER) in alkaline media. • Enhanced hydroxyl adsorption and charge redistribution at the interface improved catalytic performance. • Electrochemical analysis revealed the highest double-layer capacitance (Cdl) and electrochemically active surface area (ECSA) for 60%CMO-STO. • The heterojunction demonstrated the lowest Tafel slope, indicating improved reaction kinetics and charge transfer efficiency. Developing efficient and cost-effective bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) by modulation of the electronic states is critical for sustainable hydrogen production. In this study, we engineered a heterojunction between CoMoO 4 (CMO) and SrTiO 3 (STO). The p-n junction between CMO and STO tunes their electronic structure and redistributes the surface charges. The positive charge induced by the p-n junction offers greater adsorption of hydroxyls on the surface of the electrocatalysts. The optimized 60% CMO/STO heterojunction exhibited the most promising bifunctional activity, achieving the lowest overpotential of 102 mV for HER and 280 mV for OER in alkaline media. Electrochemical studies revealed that the 60% CMO/STO shows the highest double-layer capacitance (Cdl) and the largest electrochemically active surface area (ECSA), indicating superior charge transfer and active site availability. Moreover, based on work functions, the enhanced electron transfer and optimized hydroxyl ions adsorption due to the position charge distribution result in superior HER and OER performance. Additionally, it demonstrates the smallest Tafel slope, highlighting its enhanced reaction kinetics. This work highlights the role of heterojunction and interfacial electron transfer descriptors for enhanced OER and HER performance of the p-n junction, providing a venue to design a new electrocatalytic system for bifunctional activities.