Formation of C3N4 thin films through the stoichiometric transfer of the bulk synthesized gC3N4 using RFM sputtering

Abstract

A new approach to form stoichiometric C3N4 thin films through radio frequency magnetron (RFM) based sputtering method, compacted gC3N4 powder is used as the sputtering target. Thin-film samples are deposited on different substrates under Ar and N2 as plasma media for different durations. These samples are analyzed by scanning electron microscope, transmission electron microscope, atomic force microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction analysis. The photoelectrochemical (PEC) studies including chopped light voltammetry, incident photo-to-current conversion efficiency, and electrochemical impedance spectroscopy along with photoluminescence (PL) studies are also performed on C3N4/TiO2 heterojunction samples formed through the RFM sputtering technique. The use of Ar as the plasma medium allows the formation of a thin film of stoichiometric C3N4 in the C3N4/TiO2 heterojunction sample. The PEC and PL studies concluded that the C3N4/TiO2 heterojunction formed under Ar plasma offered a higher current density and lower impedance as compared to that offered by the C3N4/TiO2 heterojunction formed under N2 plasma. It signifies the beneficial use of compressed C3N4 as the sputtering target to form a stoichiometric and photoactive C3N4 thin films without the difficulty in controlling the N2 gas flow rate with graphite as the target in the sputtering process.