Photoelectrochemical properties of Cu2O/PANI/Si-based photocathodes destined for CO2 conversion

The present study was aimed to convert CO2 into value-added products such as methanol which not only could address the potential solution for controlling the CO2 concentration level in the atmosphere but also can offer an alternative approach for the production of renewable energy sources. In this perspective, various hybrid photoelectrocatalysts were synthesized, characterized and used as photocathodes for photoelectrocatalytic (PEC) reduction of CO2 to methanol in aqueous medium under visible light irradiation. Flat silicon (Siflat) and pyramidal textured silicon (SiPY) substrates, covered with polyaniline (PANI) with or without sensitization with copper oxide (Cu2O) particles were investigated. It was noticed that the combination of PANI and Cu2O greatly increased the PEC CO2 reduction to methanol owing to enhance the CO2 chemisorption capacity by the photocathode surface and at the same time facilitated the separation of photogenerated electron-hole (e−/h+) pairs. The PEC results demonstrated that the applied potential impacts the photocurrent stability. The sensitization with Cu2O effectively separate the photogenerated e−/h+ pairs and therefore, enhanced the PEC CO2 reduction activity of the hybrid photocatalyst. The best Faradaic efficiency (FE) for methanol formation reached 57.66 % which was recorded when Cu2O/PANI/SiPY heterostructure was used as photocathode at applied potential of −1.2V vs SCE.