3d–2p–5d Orbital Synergy in Electrocatalytic Hydrazine Oxidation Assisted Water Splitting with Industrial Scale Current Density
Pragya Arora, Kiran Bhadauriya, Labham Singh, Ayusie Goyal, Shalini Verma, Baghendra Singh, Apparao Draksharapu
Abstract
The hydrazine oxidation reaction (HzOR) is a promising alternative to the oxygen evolution reaction (OER) in electrolyzers due to its lower oxidation potential than water, which significantly reduces energy demands and enhances hydrogen production efficiency. Incorporating high-valent 5d metals into 3d metal hydroxides has shown great potential for enhancing water-splitting performance through strong 3d–2p–5d orbital interactions, improving charge transfer, intermediate adsorption, and reducing overpotentials. This study showcases an innovative approach to enhance the electrocatalytic performance of Co(OH) 2 through the incorporation of a high-valent 5d metal, tungsten (W 6+ ), using a straightforward electrochemical synthesis method. The incorporation of W 6+ into Co(OH) 2 led to significant Co 3d –O 2p –W 5d orbital coupling, strengthening the electronic interactions between Co and W. The high-valent W 6+ facilitated electron withdrawal from Co 2+, promoting easier access to Co 3+ sites enhancing the catalytic performance. The W-Co(OH) 2 achieved a current density of 100 mA cm –2 at a potential of 1.00 V versus RHE for the HzOR, which is notably lower than the 1.54 V versus RHE required for the OER. In a two-electrode system, substituting OER with HzOR resulted in a significant reduction in cell voltage by 0.50 V.