Highly Effective B@g-C3N4/Polyaniline Nanoblend for Photoelectrocatalytic Reduction of CO2 to Methanol

Photoelectrocatalytic (PEC) conversion of CO2 has been extensively investigated as it uses solar energy to combine CO2 and water to produce hydrocarbons. In the present work, B@graphitic carbon nitride (g-C3N4)/polyaniline (PANI) nanoblend was synthesized by in situ polymerization of aniline in the presence of B@g-C3N4 for PEC CO2 reduction. The catalyst was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy, X-ray diffraction, UV-Vis absorption spectroscopy, photoluminescence, X-ray photoelectron spectroscopy (XPS), and Mott-Schottky analysis. The PEC activity was evaluated by linear sweep voltammetry (LSV) and chronoamperometry. XRD revealed the formation of g-C3N4, while B doping was confirmed by XPS. The presence of PANI was visualized by FESEM. A remarkable cathodic current associated with CO2 reduction was observed during LSV from an onset potential of -0.01 V vs. normal hydrogen electrode (NHE), which is more positive than that of B@g-C3N4 (-0.82 V vs. NHE), and the positive shift is attributed to the slow charge recombination kinetics of B@g-C3N4/PANI as evidenced by PL results. The mechanism of PEC CO2 reduction was investigated and discussed on the basis of the Mott-Schottky results. In conclusion, B@g-C3N4/PANI opens a new avenue to develop photoelectrocatalysts for PEC CO2 reduction to methanol.