Precursor-Driven Reconfiguration of Bulk and Interface Enhances the Solar-Driven Water-Splitting Performance of Carbon Nitride Photoanode

Abstract

Carbon nitride (CN) has emerged as a promising metal-free semiconductor for photoelectrochemical (PEC) water-splitting applications. However, its practical implementation is hindered by low photoactivity compared with inorganic photoanodes. We report the excellent photoactivity of modified CN photoanodes for PEC water oxidation. Incorporating powder precursors during the synthesis induces favorable morphological modifications, enhanced layer ordering, and charge transfer. The powder thiourea-assisted growth of CN boosted the photocurrent by almost 3-fold. This enhancement is attributed to suppressed carrier recombination, improved charge transfer, and the formation of CN and SnS2 heterojunctions. The champion CN photoanode achieved an excellent charge extraction efficiency of up to 69% and a benchmark photocurrent density with and without a hole scavenger of about 2.7 and 2 mA cm-2, respectively for water oxidation at 1.23 V versus RHE in neutral 0.1 M Na2SO4 solution, with an onset potential of 0.32 V vs RHE and external quantum yield reaching 42% at 440 nm.