New research indicates a groundbreaking process for high-efficiency water electrolysis, offering a potential solution to the challenges hindering the scale-up of green hydrogen production.
Traditional electrolysis technologies have struggled to compete with low-cost grey hydrogen produced from fossil fuels, but this innovative approach could reduce system costs. A key cost is a membrane used to keep the hydrogen and oxygen gases separate.
The newly proposed process achieves continuous and isothermal operation without the need for expensive membranes, addressing operational challenges faced by previous decoupled water electrolysis (DWE) methods. The system operates in a near-neutral electrolyte of NaBr in water, using a soluble redox couple (SRC) involving bromide and bromate. In one cell, bromide is electro-oxidised to bromate while hydrogen evolves, and in another cell, bromate is chemically reduced to bromide, releasing oxygen. This membraneless DWE process demonstrates high faradaic and electrolytic efficiency, with a faradaic efficiency of 98%, outperforming previous DWE methods.
The researchers overcame challenges associated with batch operation and thermal swings by using a reversible redox potential in the bromide/bromate couple. The process introduces an electrochemical and chemical cycle that divides the oxygen evolution reaction into two sub-reactions, enabling continuous operation with remarkable efficiency. The study suggests that this breakthrough may lead to a competitive technology for large-scale green hydrogen production, emphasising the importance of replacing certain materials with earth-abundant alternatives and integrating the electrolytic and catalytic subprocesses for long-term performance validation.
Research is also improving the photocatalysis and electrocatalysis for producing hydrogen.
Source
Electrochemical and chemical cycle for high-efficiency decoupled water splitting in a near-neutral electrolyte, Nature Materials, 2024-01-09
Boˆreal 