Xiao Cheng,Rong Chen,Xun Zhu,Qiang Liao,Liang An,Dingding Ye,Xuefeng He,Shuzhe Li,Lin Li
The development of highly efficient photocatalytic reactor is of importance to improve the performance of the photocatalytic reduction of CO 2 . In this work, an optofluidic planar microreactor is designed and fabricated for the photocatalytic reduction of CO 2 with liquid water in alkaline environment . Such design offers several advantages of large surface-area-to-volume ratio, enhanced mass and photon transfer and more uniform light distribution. The performance of the developed planar microreactor is evaluated by measuring the methanol concentration to estimate the methanol yield under various operating parameters, including the liquid flow rate , light intensity, catalyst loading and NaOH concentration. It is shown that increasing the liquid flow rate firstly improves and then decreases the methanol concentration while the methanol yield continuously increases as the liquid flow rate increases. The increase of the light intensity and NaOH concentration increases both the methanol concentration and yield. Increasing the catalyst loading firstly improves the performance and then results in the reduction of the performance. A maximum methanol yield of 454.6 μmole/g-cat·h is achieved under a liquid flow rate of 50 μL/min, 0.2 M NaOH, and the light intensity of 8 mW/cm 2 .
Cu 2 O films were prepared using an improved solution immersion method, whereas ZnO/Cu 2 O films were prepared using an electrodeposition method. Then, the pure Cu 2 O film electrodes and ZnO/Cu 2 O film electrodes were used to reduce CO 2 to CH 3 OH. The crystal structure, morphology, particle size, and specific surface area of pure Cu 2 O films prepared under different immersion times and ZnO/Cu 2 O films prepared under different deposition times and Zn 2+ concentrations were analyzed using X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller analysis. The electrolytic activity of the pure Cu 2 O film electrodes and ZnO/Cu 2 O film electrodes were studied. Under the same reaction conditions, the ZnO/Cu 2 O film electrode with the Zn 2+ concentration of 0.05 M and the deposition time of 30 min had the highest total CH 3 OH yield of 315.656 μmol/cm 2 and the fastest formation rate of 52.609 μmol/(cm 2 h), and its faradaic efficiency was 45%, which was remarkably higher than that of pure Cu 2 O film electrodes under the same reaction conditions. This study highlighted that ZnO nanoparticles had a very good promotion of electrolytic CO 2 reduction on Cu 2 O film.
CdSeTe nanoparticles (CdSeTe NPs)/TiO 2 nanotubes (TiO 2 NTs) and CdSeTe nanosheets (CdSeTe NSs)/TiO 2 NTs were fabricated by photoelectric deposition method and hydrothermal method, respectively. The band gap of the CdSeTe NPs/TiO 2 NTs (1.24 eV) is narrower than that of the CdSeTe NSs/TiO 2 NTs (1.48 eV). The photoelectrochemical conversion efficiency of the CdSeTe NPs/TiO 2 NTs is 2.72 times larger than that of the CdSeTe NSs/TiO 2 NTs, manifesting that the CdSeTe NPs/TiO 2 NTs possessed more excellent photocatalytic performance. Furthermore, the current density of electrocatalytic reduction CO 2 on the CdSeTe NPs/TiO 2 NTs was 2.47 times larger than that of the CdSeTe NSs/TiO 2 NTs, showing the excellent electrocatalytic performance of the CdSeTe NPs/TiO 2 NTs. The major product methanol was detected in the PEC reduction process on the two as-prepared materials. The yield reached 18.57 mmol L −1 after 300 min on CdSeTe NPs/TiO 2 NTs, which is 16 times larger than that of CdSeTe NSs/TiO 2 NTs.
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