Hetero-structure CdS–CuFe2O4 as an efficient visible light active photocatalyst for photoelectrochemical reduction of CO2 to methanol

In the present paper, hetero-structured CdS–CuFe 2 O 4 nanocomposite was synthesized by a facial method to convert CO 2 to methanol in the photoelectrochemical (PEC) system. The synthesized catalysts were characterised by XRD, Raman spectroscopy, TEM, FESEM, EDX, XPS, UV–vis and PL spectroscopy. The CdS–CuFe 2 O 4 photocatalyst showed ~6 times higher photocurrent compared to the CuFe 2 O 4 at −0.35 V vs. NHE of bias potential under CO 2 environment as revealed by chronoamperometry results. Incident photon to current efficiency (IPCE) for CuFe 2 O 4 and CdS–CuFe 2 O 4 at 470 nm were found as 7.28 and 12.09%, respectively which clearly indicates the proficiency of CdS–CuFe 2 O 4 heterojunction to absorb the visible light resulting in e − /h + generation and the charge transfer during PEC CO 2 reduction. Products in aqueous and gas phases were analysed which confirmed the selective production of methanol with trace amounts of H 2 and CO. The CdS–CuFe 2 O 4 catalyst demonstrated 72% and 16.9% of Faradaic and quantum efficiencies, respectively in terms of methanol production where a methanol yield of 23.80 μmole/Lcm 2 was achieved in CO 2 saturated aqueous solution of NaHCO 3 (0.1 M). Detailed investigation revealed that the conduction band (CB) of the CdS in the heterojunction catalyst could act as a CO 2 reduction site by trapping photogenerated electrons from the highly photosensitive CuFe 2 O 4 while the water oxidation could take place at the valance band (VB) of CuFe 2 O 4 . • Hetero-structure CdS–CuFe 2 O 4 was fabricated via facile method. • Incident photon to current efficiency was found as ~12% in CdS–CuFe 2 O 4 . • Suitable bandgap and band edge positions for photoelectrochemical CO 2 reduction. • Methanol yield over CdS–CuFe 2 O 4 was increased by ~91% compared to the CuFe 2 O 4 . • Faradaic and quantum efficiency for methanol production were found 72% and 16.9%.