Multi-heteroatom-doped carbon from waste-yeast biomass for sustained water splitting

Producing hydrogen in clean, affordable and safe manners without damaging the environment can help address the challenge of meeting a growing energy demand sustainably. Yeast biomass-derived materials—such as multi-heteroatoms (nitrogen, sulfur and phosphorus) doped carbon (MHC) catalysts from waste biomass—can help develop efficient, eco-friendly and economical catalysts to improve the sustainability of hydrogen production. Here we report hydrogen and oxygen production in 1 M potassium hydroxide using ruthenium single atoms (RuSAs) along with Ru nanoparticles (RuNPs) embedded in MHC (RuSAs + RuNPs@MHC) as a cathode and magnetite (Fe₃O₄) supported on MHC (Fe₃O₄@MHC) as an anode. The RuSAs + RuNPs@MHC catalyst outperforms the state-of-the-art commercial platinum on carbon catalyst for hydrogen evolution reaction in terms of overpotential, exchange current density, Tafel slope and durability. Furthermore, compared with industrially adopted catalysts (that is, iridium oxide), the Fe₃O₄@MHC catalyst displays outstanding oxygen evolution reaction activity. For whole water splitting, it requires a solar voltage of 1.74 V to drive ~ 30 mA, along with remarkable long-term stability in the presence (12 h) and absence (58 h) of outdoor-sunlight exposure, as a promising strategy towards a sustainable energy development.