Yunxia Bai,Mei Li,Xuemei Liu,Jinyu Han,Xinli Zhu,Qingfeng Ge,Hua Wang
Photocatalytic CO2 reduction is a promising route to simultaneously address two critical issues related to the energy and environment. Herein, a direct Z-scheme photocatalytic system, Ti3+ defective TiO2/CdS nanoflowers, was fabricated to enhance the production of C1–C3 products from CO2 reduction. First, nanoflower-like TiO2 (NF-TiO2) is prepared using a TiB2 precursor to build in Ti3+ defects. Then, the NF-TiO2/CdS heterojunctions are constructed via the sulfurization of TiO2/Cd-MOF. Importantly, the optimal heterojunction photocatalyst NF-TiO2/CdS0.6 exhibits a highly promoted CO2 reduction activity not only for CO and CH4 but also for C2–C3 hydrocarbons. The cumulative yields of CO and CH4 are 1007.0 μmol/g and 83.5 μmol/g (2.5 h), respectively, and a yield of 55.3 μmol/g (2.5 h) of C2–C3 hydrocarbons is obtained. This enhanced yield of C1–C3 products is attributed to the synergistic effects of abundant Ti3+ defects that increase adsorption and activation of CO2, the large surface area that provides sufficient active sites, and a direct Z-scheme heterojunction with a good intimate contact interface that effectively separates charge carriers and accumulates electrons with strong reducibility. Moreover, the photoluminescence analysis of hydroxyl radicals was conducted to provide evidence for the direct Z-scheme mechanism. This work provides a facile method for the construction of a TiO2-based direct Z-scheme photocatalytic system for improving photocatalytic performance toward CO2 reduction.
The glycerol electrochemical oxidation (GEOR) represents a sustainable strategy for converting abundant biomass-derived feedstocks into high value-added chemicals. Herein, we prepared a series of Pt/Au/Ti catalysts via electrodepositing Pt nanoparticles (NPs) onto Au-sputtered Ti substrates (Au/Ti). The atomic Pt/Au ratio on the surface was engineered through pulse-deposition cycles. The structures of the catalysts were characterized by scanning electron microscopy, atomic force microscopy and X-ray diffraction, confirming that Pt NPs were uniformly deposited on the Au/Ti surface. Electrochemical evaluations demonstrated that the 10Pt/Au/Ti catalyst has superior GEOR performance in 1 M KOH solutions, achieving a peak current density of 13.16 mA cm −2 . Operando electrochemical impedance spectroscopy revealed that Au and Pt worked synergistically to promote the adsorption of adsorbed hydroxyl species ( OH ad ) and glycerol, thereby improving GEOR activity. Product analysis revealed that the 10Pt/Au/Ti catalyst yielded the highest glyceric acid selectivity of 93.6% at 0.9 V vs. RHE under alkaline conditions. This study provides an efficient strategy for the highly selective conversion of glycerol into high value-added C 3 products.
Photocatalytic selective oxidation of glycerol to value-added C 3 products is a promising strategy for the valorization of glycerol. In this work, an inorganic/organic composite material by integrating zinc oxide (ZnO) with iron thioporphyrazine (FePz) was prepared to act as photocatalyst for photocatalytic oxidation of glycerol in water. The effects of FePz surface modification on the physicochemical properties and photocatalytic performance of ZnO were systemically studied. More importantly, the integration of ZnO with FePz could markedly improve the visible light absorption ability and effectively promote the separation of photogenerated charges. Meanwhile, introducing FePz onto the ZnO surface was beneficial to the adsorption capacity of glycerol. Just because of this, ZnO/FePz composite exhibited excellent photocatalytic activity for oxidizing glycerol in water, C 3 products including glyceraldehyde and dihydroxyacetone were obtained from this composite photocatalytic system. Additionally, the active species responsible for glycerol oxidation were also determined.
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