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

• Published in: Angewandte Chemie Vol. 134; no. 50
• Main Authors: Pulignani, Carolina, Mesa, Camilo A., Hillman, Sam A. J., Uekert, Taylor, Giménez, Sixto, Durrant, James R., Reisner, Erwin
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 12.12.2022
• Subjects: Absorption spectroscopy; Aluminum oxide; Carbon; Carbon Nitride; Chemistry; Electrodes; Irradiation; Nanoparticles; Organic Oxidation; Oxidation; Photoanodes; Photoelectrochemistry; Radiation; Recombination; Spectroscopy; Suspension systems
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202211587

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. Carbon‐nitride‐based photoelectrodes were produced by co‐deposition of a blend of cyanamide‐functionalized carbon nitride (NCNCNx) and indium tin oxide (ITO) nanoparticles on top of thin, alumina‐coated conducting FTO‐glass. The composite photoanodes display benchmark photocurrents with a range of different alcohol substrates, a low onset potential, and an incident photon‐to‐electron conversion efficiency (IPCE) up to 60 % at 350 nm.