Human Urine-Fueled Light-Driven NADH Regeneration for Redox Biocatalysis.

Human urine is considered as an alternative source of hydrogen and electricity owing to its abundance and high energy density. Here we show the utility of human urine as a chemical fuel for driving redox biocatalysis in a photoelectrochemical cell. Ni(OH)2 -modified α-Fe2 O3 is selected as a photoanode for the oxidation of urea in human urine and black silicon (bSi) is used as a photocathode material for nicotinamide cofactor (NADH: hydrogenated nicotinamide adenine dinucleotide) regeneration. The electrons extracted from human urine are used for the regeneration of NADH, an essential hydride mediator that is required for numerous redox biocatalytic reactions. The catalytic reactions at both the photoanode and the photocathode were significantly enhanced by light energy that lowered the overpotential and generated high currents in the full cell system.