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Colloidal nanorods based on CdS or CdSe, functionalized with metal particles, have proven to be efficient catalysts for light-driven hydrogen evolution. Seeded CdSe@CdS nanorods have shown increasing performance with increasing rod length. This observation was rationalized by the increasing lifetime of the separated charges, as a large distance between holes localized in the CdSe seed and electrons localized at the metal tip decreases their recombination rate. However, the impact of nanorod length on the electron-to-tip localization efficiency or pathway remained an open question. Therefore, we investigated the photo-induced electron transfer to the metal in a series of Ni-tipped CdSe@CdS nanorods with varying length. We find that the transfer processes occurring from the region close to the semiconductor–metal interface, the rod region, and the CdSe seed region depend in different ways on the rods' length. The rate of the fastest process from excitonic states generated directly at the interface is independent of the rod length, but the relative amplitude decreases with increasing rod length, as the weight of the interface region is decreasing. The transfer of electrons to the metal tip from excitons generated in the CdS rod region depends strongly on the length of the nanorods, which indicates an electron transport-limited process, i.e., electron diffusion toward the interface region, followed by fast interface crossing. The transfer originating from the CdSe excitonic states again shows no significant length dependence in its time constant, as it is probably limited by the rate of overcoming the shallow confinement in the CdSe seed. [ABSTRACT FROM AUTHOR]

CuZnO/Al2O3 is the industrial catalyst used for methanol synthesis from syngas (CO + H2) and is also promising for the hydrogenation of CO2 to methanol. In this work, we synthesized Al2O3 nanorods (n-Al2O3) and impregnated them with the CuZnO component. The catalysts were evaluated for the hydrogenation of CO2 to methanol in a fixed-bed reactor. The support and the catalysts were characterized, including via in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The study of the CO2 adsorption, activation, and hydrogenation using in situ DRIFT spectroscopy revealed the different roles of the catalyst components. CO2 mainly adsorbed on the n-Al2O3 support, forming carbonate species. Cu was found to facilitate H2 dissociation and further reacted with the adsorbed carbonates on the n-Al2O3 support, transforming them to formate or additional intermediates. Like the n-Al2O3 support, the ZnO component contributed to improving the CO2 adsorption, facilitating the formation of more carbonate species on the catalyst surface and enhancing the efficiency of the CO2 activation and hydrogenation into methanol. The synergistic interaction between Cu and ZnO was found to be essential to increase the space–time yield (STY) of methanol but not to improve the selectivity. The 3% CuZnO/n-Al2O3 displayed improved catalytic performance compared to 3% Cu/n-Al2O3, reaching a CO2 conversion rate of 19.8% and methanol STY rate of 1.31 mmolgcat−1h−1 at 300 °C. This study provides fundamental and new insights into the distinctive roles of the different components of commercial methanol synthesis catalysts. [ABSTRACT FROM AUTHOR]

Converting CO 2 into energy-rich fuels by using solar energy is a sustainable solution that promotes a carbon-neutral economy and mitigates our reliance on fossil fuels. However, affordable and efficient CO 2 conversion remains an ongoing challenge. Here, we introduce polymeric g-C 3 N 4 into the pores of a hollow In 2 O 3 microtube. This architecture results in a compact and staggered arrangement between g-C 3 N 4 and In 2 O 3 components with an increased contact interface for improved charge separation. The hollow interior further contributes to strengthening light absorption. The resulting g-C 3 N 4 -In 2 O 3 hollow tubes exhibit superior activity (274 μmol·g -1 ·h -1 ) toward CO 2 to CO conversion in comparison with those of pure In 2 O 3 and g-C 3 N 4 (5.5 and 93.6 μmol·g -1 ·h -1 , respectively), underlining the role of integrating g-C 3 N 4 and In 2 O 3 in this advanced system. This work offers a strategy for the advanced design and preparation of hollow heterostructures for optimizing CO 2 adsorption and conversion by integrating inorganic and organic semiconductors.