New insight into photoelectric converting CO2 to CH3OH on the one-dimensional ribbon CoPc enhanced Fe2O3 NTs

Abstract The Fe2O3 NTs was in situ prepared by the anodic oxidation method. One-dimensional ribbon cobalt phthalocyanine (CoPc-Rs) was loaded onto Fe2O3 NTs. The morphology structure analysis showed that the CoPc-Rs with length of 7.1 μm and width of 700 nm distributed on the Fe2O3 NTs surface evenly and it tended to grow toward (0 0 1) crystal plane. After assembling CoPc-Rs onto Fe2O3 NTs, on the one hand, the photocatalytic performance was enhanced due to the improvement of absorbing visible light and the relative narrower energy band gap. On the other hand, electrocatalytic ability was improved by the resistance value reduces (900 Ω) and the overpotential drops (40 mV). In the photoelectrocatalytic reduction process at −1.3 V, the net current density (iCO2 − iN2) of CoPc-Rs/Fe2O3 NTs was 7.65 times that of the Fe2O3 NTs. The overpotential of photoelectrocatalytic reduction of CO2 on CoPc-Rs/Fe2O3 NTs brought forward 100 mV than that of Fe2O3 NTs, which indicated that the CoPc-Rs/Fe2O3 NTs exerted outstanding photoelectrocatalytic reduction performance. The methanol concentration of photoelectrocatalytic reduction of CO2 was 138 μmol L−1 cm−2, it was greater than the simple addition (126 μmol L−1 cm−2) of photocatalysis and electrocatalysis, which embodied the excellent synergistic effect of photocatalytic reduction and electrocatalytic reduction. The faradaic current efficiency reached up to 84.6% at present.