Highly-active direct Z-scheme Si/TiO₂ photocatalyst for boosted CO₂ reduction into value-added methanol

Abstract

In the present study, direct Z-scheme Si/TiO 2 photocatalyst was synthesized via a facile hydrothermal reaction using tetrabutyl titanate and Si powder prepared from magnesiothermic reduction of SiO 2 nanospheres. The Si/TiO 2 nanospheres were composed of porous Si nanospheres with a diameter of $300 nm and TiO 2 nanosheets with a diameter of 50 nm and thickness of 10 nm, and demonstrated superior visible light harvesting ability to either Si nanospheres or TiO 2 nanosheets. CO 2 photocatalytic reduction proved that Si/TiO 2 nanocomposites exhibit high activity in conversion of CO 2 to methanol with the maximum photonic efficiency of 18.1%, while pure Si and TiO 2 catalyst are almost inactive, which can be ascribed to the integrated suitable band composition in the Si/TiO 2 Z-scheme system for CO 2 reduction. The enhanced photocatalytic property of Z-scheme Si/TiO 2 nanospheres was ascribed to the formation of Si/TiO 2 Z-scheme system, which improved the separation efficiency of the photogenerated carriers, prolonged their longevity, and therefore boosted their photocatalytic activity.

Photocoupled Bioanode: A New Approach for Improved Microbial Fuel Cell Performance

“…A CH 4 evolution rate of 1.10 ppm cm −2 h −1 for the TNT photoanode is observed in Figure . Control tests in which Ar is used instead of CO 2 are well established to estimate the carbon source, contaminant or CO 2 , under identical conditions of irradiation . If an Ar/H 2 O(g) mixture was used instead of CO 2 /H 2 O(g), no hydrocarbons were detected.…”

“…The normal MFC was measured under dark conditions. The Coulombic efficiency ( E C ) for the normal MFC and the hybrid MFC (under illumination) was calculated by Equation (2) using the data for 48 h of continuous operation …”

“…Control tests in which Ar is used instead of CO 2 are well established to estimate the carbon source,c ontaminanto rC O 2 ,u nder identical conditionso fi rradiation. [42][43][44][45][46][47][48] If an Ar/H 2 O(g) mixture was used insteadofC O 2 /H 2 O(g), no hydrocarbons were detected.…”

“…Thep ower density (PD) was calculated using PD = VI/A,i nw hich V = voltage, I = current, and A = projected area of the cathode.F or the hybrid MFC,t he polarization curve was measured under continuous illumination by using a1 00 WX enon solar simulator (LCS-100, Oriel, USA) with an AM1.5 filter.T he normal MFC was measured under dark conditions.T he Coulombic efficiency( E C ) for the normal MFC and the hybrid MFC (under illumination) was calculated by Equation (2) using the data for 48 ho fc ontinuous operation. [48] Coulombic efficiency E C ðÞ ¼…”

Efficient Photocatalysts Made by Uniform Decoration of Cu2O Nanoparticles on Si Nanowire Arrays with Low Visible Reflectivity

“…Therefore, in this study, such limitations were overcome by adapting the two-step electroless deposition in order to achieving uniform incorporation of Cu-oxide nanoparticles with the SiNW arrays. In addition, the controlled formation of heterostructural n-type Cu 2 O/p-type Si could be particularly potential to act as efficient photocatalysts [13] because the photo-excited electrons and holes might be separated to initiate photodegradation reaction of dye removal prior to rapid carrier recombination [14, 15]. Based on such designs, investigations of surface morphologies, chemical compositions, and crystallographic analysis were performed to characterize the synthesized Cu 2 O/Si nanostructures.…”