New Discovery: Biomass sugars may reduce cost of green hydrogen

Scientists from China and Singapore have unveiled a solar-powered co-electrolysis technology that could significantly lower the cost of green hydrogen while simultaneously upgrading biomass-derived sugars into value-added chemicals. The study shows that hydrogen can be produced at costs projected to undercut fossil-based routes by replacing the energy-intensive oxygen evolution reaction with selective oxidation of glucose.

The system couples water electrolysis with glucose oxidation using a copper-doped cobalt oxyhydroxide catalyst. This approach reduces the anodic potential by nearly 400 millivolts, sharply cutting electricity demand. In a membrane-free reactor powered by a triple-junction InGaP/GaAs/Ge photovoltaic device, the setup achieved hydrogen production rates exceeding 500 micromoles per hour per square centimeter.

Solar-driven electrolysis is seen as a key pathway for zero-carbon hydrogen, but high energy requirements have limited its commercial viability. Biomass sugars derived from non-food cellulose offer a lower-energy oxidation alternative and generate chemical products, yet controlling these reactions has remained challenging.

The research team addressed this by designing a catalyst that selectively converts glucose into formate, a valuable industrial chemical, while sustaining high hydrogen output.

According to the researchers from China Agricultural University and Nanyang Technological University, introducing 5 mol percent copper into cobalt oxyhydroxide increased formate selectivity from about 50 percent to 80 percent and enabled more efficient co-electrolysis.

Advanced spectroscopic and microscopic analyses revealed that copper stabilizes key reactive sites on the catalyst surface, suppressing unwanted side reactions. Computational studies further showed that copper promotes a controlled reaction pathway that releases formate from each carbon atom in the sugar molecule.

On the cathode side, pairing the anode with a nickel–molybdenum electrode enabled high-purity hydrogen generation with nearly 100 percent Faradaic efficiency. Under concentrated sunlight, the device delivered stable performance over 24 hours of continuous operation.

Economic modelling suggests the integrated process could reduce the levelized cost of hydrogen to around $1.54 per kilogram. By combining lower energy input, a membrane-free design and revenue from formate co-production, the technology points to a scalable route for cost-competitive green hydrogen linked to biomass valorisation and the circular bioeconomy.