Selective photo-reduction of CO 2 to methanol using Cu-doped 1D-Bi 2 S 3 /rGO nanocomposites under visible light irradiation

• Published in: New journal of chemistry 2023-01, Vol.47 (3), p.1422-1434
• Main Authors: Mandal, Arindam, Maitra, Soumyajit, Roy, Subhasis, Hazra, Baisakhi, Ray, Koustuv, Kargupta, Kajari
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/D2NJ03892G

A novel Cu-doped one dimensional (1D) Bi 2 S 3 rod-shaped nanocapsule/rGO composite is explored as a photocatalyst for selective reduction of CO 2 to methanol. In particular, the effects of Cu doping of rGO supported Bi 2 S 3 on band gap tuning and on product selectivity are investigated. Bi 2 S 3 rod-shaped nanocapsules and 0.5, 1, and 2 weight percent Cu-doped Bi 2 S 3 /rGO are synthesised through a hydrothermal approach. The photocatalysts are characterized by XRD, FTIR, UV-Vis spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, and SEM, TEM and EDX analysis. It is revealed that Cu-doped Bi 2 S 3 /rGO for all different compositions offers selective and enhanced production of methanol compared to undoped Bi 2 S 3 /rGO, pristine Bi 2 S 3 , and Cu-doped Bi 2 S 3 which produce formic acid along with methanol. The optimum 1 weight percent Cu-doped Bi 2 S 3 /rGO photocatalyst, exhibiting the smallest band gap and the lowest rate of recombination of electron–hole pairs, offers the highest photocatalytic activity of 719 μmol g cat. −1 h −1 . DFT studies corroborate the experimental finding of a drastic reduction of the band gap (1.36 eV) of Cu-doped Bi 2 S 3 /graphene and unveil that Cu 3d–C 2p hybridization as well as enhancement of Bi 6p–C 2p hybridization in the presence of copper significantly increases the overall DOS of the system at the Fermi level, resulting in enhancement of electronic conductivity and charge transfer; further deformation in the graphene sheets due to the presence of Cu-Bi 2 S 3 creates CO 2 trapping sites for its efficient adsorption and selective photoreduction.