Rational Design of Carbon Nitride Photoelectrodes with High Activity Toward Organic Oxidations

Abstract

Carbon nitride (CNx) is a light-absorber with excellent performance in photocatalytic suspension systems, but the activity of CNx photoelectrodes has remained low. Here, cyanamide-functionalized CNx (NCNCNx) was co-deposited with ITO nanoparticles on a 1.8 Å thick alumina-coated FTO electrode. Transient absorption spectroscopy and impedance measurements support that ITO acts as a conductive binder and improves electron extraction from the NCNCNx, whilst the alumina underlayer reduces recombination losses between the ITO and the FTO glass. The Al2O3|ITO : NCNCNx film displays a benchmark performance for CNx-based photoanodes with an onset of −0.4 V vs a reversible hydrogen electrode (RHE), and 1.4±0.2 mA cm−2 at 1.23 V vs RHE during AM1.5G irradiation for the selective oxidation of 4-methylbenzyl alcohol. This assembly strategy will improve the exploration of CNx in fundamental and applied photoelectrochemical (PEC) studies.