The photosynthesis of methanol on 1D ordered Zn:CuInS2 nanoarrays

• We synthesized CuInS2 highly ordered nanoarrays by the chemical bath deposition method, with the anodized aluminum oxide (AAO) arrays as a template.
• The n-type and p-type Zn doped CuInS2 were fabricated as the forms of thin films and nanoarrays.
• The maximum photocurrent density of the sample was found to be −2.10 mA/cm2.
• The CuInS2 highly ordered nanoarrays have good performance in methanol production.

CO2-to-CH3OH hydrogenation reaction is one of the promising solutions not only to reduce the global warming impact by the elimination of greenhouse gases but also to produce valuable chemicals directly from carbon dioxide. In this study, pure and Zn-doped CuInS2 highly ordered nanoarrays were fabricated by the chemical bath deposition method, accompanied with the anodized aluminum oxide (AAO) arrays as a template. Structure, morphological, optical, and photoelectrochemical properties for the nanoarrays were investigated. The crystalline and morphology of the arrays were characterized by means of X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD results show that main peak of CuInS2 shifts to the higher angles when the doping concentrations of Zn increase. As molar ratios of Zn in the bath solution were higher than 0.4, the semiconductor property of the sample changed from n-type to p-type from Hall measurement. The carrier densities of the Zn-doped CuInS2 arrays were found to be in the range of 1.32 × 1017–9.45 × 1020 cm−3. The maximum photocurrent density was 2.02 mA/cm2 for the p-type CuInS2 arrays with Zn-doped molar ratios of 0.4. Time-dependent solid phase reactions were monitored by the diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). Additionally, the quadrupole mass spectroscopy (MS) accompanied with gas chromatograph (GC) was used for the gas phase analysis. The maximal methanol production rate during the photocatalysis was found to be 0.032 M/h, which is better than that of the referenced CBD film (0.003 M/h) prepared in the same compositions.