Synthesis of Cu2O from modified Fehling reaction for the preparation of Cu2O thin film photocathode by using the spin coating method, characterization, and its photoelectrochemical properties

Abstract

Hydrogen energy has the potency as a renewable energy source to replace the fossil energy. It can be obtained through the process of photoelectrochemical (PEC) water splitting with the help of a semiconductor as a photocathode to capture photon energy. One of the copper-based metal oxide semiconductors that can be used in the water splitting process is copper(I) oxide (Cu2O), because it has non-toxic advantage, requires an easy synthesis process, low production cost, and has a low band gap (2-2.45 eV). This study aims to determine the effect of Fehling's modification using citrate in Cu2O synthesis as material to prepare Cu2O thin film photocathode using spin-coating method. The prepared photocathode consists of three stages, namely variations of Cu2O synthesis with mole ratios of copper:citrate of 1:1; 1:2; 1:4, thin film preparation and heating. Then the obtained thin film was characterized using SEM, EDX and XRD. J-V curves of the photocathodes gave current densities, onset potential and applied bias to photon efficiency (ABPE) for Cu2O thin film photocathode prepared by copper:citrate mole ratios of 1:1; 1:2; 1:4 namely 0.09; 0.18; 0.12 mA/cm2 at potential of 0.2 V (vs. RHE), 0.04; 0.08; 0.02 V (vs. RHE), and 0.062, 0.057, 0.058 %, respectively. SEM analysis result showed a spherical morphology of Cu2O. EDX analysis showed that the sample contained copper and oxygen with 78% Cu and 22% O. XRD analysis results showed the presence of Cu2O with an average crystal grain size of 38.08 nm.