High-Photovoltage Silicon Nanowire for Biological Cofactor Production.

Photocathodic conversion of NAD + to NADH cofactor is a promising platform for activating redox biological catalysts and enzymatic synthesis using renewable solar energy. However, many photocathodes suffer from low photovoltage, consequently requiring a high cathodic bias for NADH production. Here, we report an n + p-type silicon nanowire (n + p-SiNW) photocathode having a photovoltage of 435 mV to drive energy-efficient NADH production. The enhanced band bending at the n + /p interface accounts for the high photovoltage, which conduces to a benchmark onset potential [0.393 V vs the reversible hydrogen electrode (V RHE )] for SiNW-based photocathodic NADH generation. In addition, the n + p-SiNW nanomaterial exhibits a Faradaic efficiency of 84.7% and a conversion rate of 1.63 μmol h -1 cm -1 at 0.2 V RHE , which is the lowest cathodic potential to achieve the maximum productivity among SiNW-sensitized cofactor production.