No abstract

An all-inorganic perovskite (CsPbBr3) was introduced into g-C3N4 to fabricate the CsPbBr3@g-C3N4 photocatalyst for photochemical reduction in diluted CO2.

At present, the fixation of CO2 always requires it to be extracted from the atmosphere first, which leads to more energy consumption. Thus, direct photoreduction of low‐concentration CO2 to useful chemicals (e.g., syngas) under sunlight is significant from an energy‐saving and environmentally friendly perspective. Here, the design and fabrication of a [Ru(bpy)3]/[Co20Mo16P24] composite is demonstrated for visible‐light‐driven syngas production from diluted CO2 (3–20 %) gas with a high yield of approximately 1000 TONs (turnover number of syngas). This activity is an order of magnitude higher than the reported system with [Ru(bpy)3]2+ participation. With evidence from ultrafast transient absorption, GC‐MS, 1H NMR spectroscopy and in situ transient photovoltage tests, a clear and fundamental understanding of the highly efficient photoreduction of CO2 by the [Ru(bpy)3]/[Co20Mo16P24] composite is achieved. Making use of the structure and property designable polyoxometalates towards the photo‐fixation of CO2 is a conceptually distinct and commercially interesting strategy for making useful chemicals and environmental protection.

CO2 photoreduction is a promising avenue to alleviate climate change and energy shortage, and highly active and selective photocatalysts have been pursued. Discrete metal–organic cages (MOCs) with tunable structures and dispersion not only render integration of multiple functional moieties but also facilitate the accessibility of catalytic sites, yet the studies of MOCs on CO2 reduction are still underexplored. Herein, a single molecular cage of the Ir­(III) complex-decorated Zr-MOC (IrIII-MOC-NH2) is proposed for CO2 photoreduction. IrIII-MOC-NH2 shows high reactivity and selectivity in converting CO2 into CO under visible light. The selectivity is of 99.5% and the turnover frequency reaches ∼120 h–1 which is 3.4-fold higher than that of bulk IrIII-MOC-NH2 and two orders of magnitude higher than that of the classical metal–organic framework counterpart (IrIII-Uio-67-NH2). The apparent quantum yield is up to 6.71% that ranks the highest among the values reported for crystalline porous materials. Moreover, aggregation-induced deactivation of the Ir­(III) complex is restrained after incorporating into MOC-NH2. The density functional theory calculations and dedicated experiments including cyclic voltammetry, mass spectrometry and in situ IR show that the Ir­(III) complex is the catalytic center, and −NH2 in the framework plays the synergetic role in the stabilization of the transition state and CO2 adducts.

Halide perovskites have been employed as photocatalysts for CO 2 photoreduction due to their excellent optical properties and unique electronic structure. However, their photocatalytic performance is relatively poor. Herein, we demonstrate a new strategy with Mn-doped CsPb(Br/Cl) 3 mixed-halide perovskites as catalysts to enhance the efficiency of CO 2 photoreduction. By tuning the content of Mn, a series of CsPb(Br/Cl) 3 :Mn perovskites are obtained and show high efficiency in CO 2 conversion to CO and CH 4 . For the optimum catalyst sample, especially, the yields of CO and CH 4 reach 1917 μmol g −1 and 82 μmol g −1 which are 14.2 and 1.4 times higher than those of CsPbBr 3 . This work provides new insights into improving the reactivity of perovskites in CO 2 photoreduction.

Summary of main observation and conclusion An efficient and environmentally benign electrochemical oxidative radical C—H trifluoromethylation of arenes by employing Langlois reagent as the CF3 source was developed in this work. Neither transition metal catalysts nor external chemical oxidants were required in this trifluoromethylation process. The reaction could be conducted in gram scale with high reaction efficiency.

No abstract

The direct usage of CO 2 in the flue gas to produce fuels or chemicals is of great significance from energy-saving and low-cost perspectives, yet it is still underexplored. Herein, we report the photoreduction of CO 2 from the simulated industrial exhaust by synergistic catalysis of TEOA and a metal-free composite (COF1-g-C 3 N 4 ) fabricated via covalently grafting COF1 with g-C 3 N 4 . The hydrogen bond interaction between TEOA and hydrazine units on COF1 is detected in diluted CO 2 , which leads to significantly enhanced light absorption in the whole visible-light region. Also, the photo-induced electrons undergo fast transfer from COF1 to g-C 3 N 4 . This kind of dynamic interface with enhanced light absorption and electron transfer effects promotes the photosynthetic yield of syngas to 165.6 μmol•g −1 • h −1 with the use of simulated exhaust gas as a raw material directly. The photosynthetic yield of syngas ranks among the highest of known metal-free catalysts in diluted CO 2 . This work provides a general rule for designing efficient catalysts via a controlled catalytic interface and new insights into the role of TEOA in photochemical CO 2 reduction.