Researchers from China's Yunnan Normal University, the State Key Laboratory of Advanced Metallurgy for Non-ferrous Metals and Kunming University of Science and Technology have developed a graphene-based electrocatalyst that delivers efficient oxygen evolution reaction (OER) performance while using an ultra-low amount of iridium. The work showcases how biomass-derived graphene can actively boost catalytic activity and, at the same time, reduce dependence on scarce noble metals.
The study focuses on proton exchange membrane (PEM) water electrolysis, a leading technology for green hydrogen production in which the OER at the anode remains a major bottleneck due to slow kinetics and high energy consumption. Iridium is one of the few materials that are sufficiently active and stable for OER under acidic PEM conditions, but its high cost and limited availability make it essential to minimize Ir usage.
In this work, the researchers produced graphene nanosheets from waste corn stover via KOH activation, creating a material with ultra-high surface area, abundant structural defects and a high concentration of oxygen-containing functional groups. Compared with conventional graphene production routes, this biomass-derived method is simpler, more sustainable and leverages low-cost agricultural waste, while yielding a structure particularly well suited for electrocatalysis.
The engineered graphene acts as far more than an inert support. Its porous structure offers numerous anchoring sites for iridium nanoparticles, enabling uniform dispersion and high atomic utilization of the precious metal. At the same time, the conductive graphene network promotes efficient electron transport, while surface functional groups help to stabilize the Ir nanoparticles and suppress their migration and aggregation during operation, improving durability.
Using this platform, the team constructed an Ir₀.₃/S-GNSs-750 heterostructure catalyst with very low iridium loading. The strong interaction between the defect-rich, oxygen-functionalized graphene and the Ir modifies the electronic structure of the active sites, optimizing the adsorption of key OER intermediates. This tuning changes the OER mechanism: the rate-limiting step switches from the relatively energy-intensive OH → O transition to the more favorable O → OOH step, which reduces the theoretical overpotential from 0.74 V to 0.56 V and indicates a marked improvement in reaction efficiency.
Overall, the work demonstrates how defect-engineered, biomass-derived graphene can function as an active component in catalyst design - simultaneously enhancing performance, stability and noble-metal efficiency - while offering a scalable route based on low-cost agricultural residues such as corn stover.
