Photoelectrochemical lactate production from pyruvate via in situ NADH regeneration over a hybrid system of CdS photoanode and lactate dehydrogenase

Lactate has been attracting much attention as a precursor for typical biodegradable plastics, poly(lactate). Lactate is industrially produced by reacting acetaldehyde with hydrogen cyanide, a highly toxic substance, and hydrolysing the resulting lactonitrile. To overcome these problems, a method of producing lactate from renewable energy and biomass-derived materials is desired. In this study, we developed a hybrid system con-sisting of CdS photoanode, lactate dehydrogenase (LDH), and Rh complex [Cp*Rh(bpy)(H2O)]2+ (Cp* = pen-tamethylcyclopentadienyl, bpy = 2,2 '-bipyridyl) as a catalyst for regioselective NAD+ reduction for photoelectrochemical lactate production from pyruvate via in situ NADH regeneration using a reversible electron donor [Fe(CN)6]4- without applied bias and toxic substances under visible light irradiation. The reduction ef-ficiency of pyruvate to lactate was estimated to be 22.8% for 4 h irradiation with average production rate of 8.6 mu mol h-1 by using photoelectrochemical system of CdS photoanode and LDH.

Automated summary

In this study, a hybrid system consisting of CdS photoanode, lactate dehydrogenase (LDH), and Rh complex [Cp*Rh(bpy)(H2O)]2+ was developed as a catalyst for photoelectrochemical lactate production. Through in situ NADH regeneration using a reversible electron donor [Fe(CN)6]4-, the reduction efficiency of pyruvate to lactate was estimated to be 22.8% with an average production rate of 8.6 μmol/h under visible light irradiation, without applied bias and toxic substances.