Chemistry Defense: Yufeng Chen: Non-precious metal nitrides for efficient electrochemical water splitting

Non-precious metal nitrides for efficient electrochemical water splitting

Growing global energy demands coupled with the detrimental environmental impacts of fossil fuel combustion highlight an urgent need to develop sustainable energy technologies. Electrochemical water splitting stands as a promising approach to convert renewable energy sources to hydrogen, a clean and carbon free energy carrier, for applications and energy transportation. However, the process requires efficient, durable, and cost-effective electrocatalysts that are still being developed. Non-precious metal nitrides have recently garnered significant attention due to their excellent catalytic properties, low cost, and high stability. This thesis focuses on several important aspects related to this catalyst family. Chapter 1 discusses recent advancements and fundamental methodologies in electrocatalyst research relevant to water splitting applications. Chapter 2 describes the system involving the development of nitridated NiMoO₄ nanoneedles as a catalyst for the hydrogen evolution reaction (HER). The optimized material shows strong HER performance in alkaline solution, with low overpotentials, favorable Tafel slopes, and stable long-term operation. Notably, the catalyst reaches a high current density of 350 mA/cm² at an overpotential of only -10 mV, showing its potential for practical hydrogen production. Chapter 3 focuses on Co₃Mo₃N nanoparticles used as a photo-thermal electrocatalyst for the oxygen evolution reaction (OER) and its improved performance under both light and heat. Electrochemical testing shows that Co₃Mo₃N catalyst has a significant photo-thermal enhancement in OER. For example, under 2 watts of blue light, it achieves a 150% increase in current density at an overpotential of 0.34 V. The outstanding effect of photo-thermal enhancement of the catalyst indicates its potential in light-assisted water-splitting technologies. Overall, this research supports the development of affordable, high-performance catalytic materials for clean energy applications.