Reduction of CO2 to methanol using renewable hydrogen is a promising but challenging strategy for carbon capture and utilization.

Conversion of CO 2 to value-added chemicals has been a long-standing objective, and direct hydrogenation of CO 2 to lower olefins is highly desirable but still challenging. Herein, we report a selective conversion of CO 2 to lower olefins through CO 2 hydrogenation over a ZnZrO/SAPO tandem catalyst fabricated with a ZnO-ZrO 2 solid solution and a Zn-modified SAPO-34 zeolite, which can achieve a selectivity for lower olefins as high as 80−90% among hydrocarbon products. This is realized on the basis of the dual functions of the tandem catalyst: hydrogenation of CO 2 on the ZnO-ZrO 2 solid solution and lower olefins production on the SAPO zeolite. The thermodynamic and kinetic coupling between the tandem reactions enable the highly efficient conversion of CO 2 to lower olefins. Furthermore, this catalyst is stable toward the thermal and sulfur treatments, showing the potential industrial application.

Hydrogenation of CO 2 to aromatics with selectivity of 73% among hydrocarbons at a single-pass conversion of 14% is achieved over a tandem catalyst. A thermodynamic coupling between CO 2 hydrogenation and aromatics formation was effectively conducted through the intermediate CH x O species. It was found that the presence of H 2 O and CO 2 not only facilitates aromatics production but also suppresses the formation of polycyclic aromatics, resulting in highly stable catalytic performance.

The N-functionalized ordered mesoporous carbons could be readily obtained by post-synthesis with nitrogen loading as high as 8.6 wt% and well preserved mesopore structure. Using NH 3 as nitrogen source dramatically increased BET surface area and pore volume of the resultant hybrid material, however, N-doping with melamine as a source resulted in the contrary results. These N-doping carbons were used as supports to immobilize small-sized Pd nanoparticles, which provided a unique platform to investigate the influences of metal nanoparticle size, mesostructural properties and N-functionalized supports on the selective hydrogenation of phenol to cyclohexanone, an important intermediate in the production of nylon 6 and nylon 66 in chemical industry. The catalyst with ultrasmall (about 1.2 nm) PdNPs gave the best reaction activity and selectivity under mild conditions. In addition, present multifunctional catalyst demonstrated excellent catalytic stability and could be used for six times without loss of product yields. These outstanding catalytic performances could be attributed to the synergetic effects of mesoporous structure, N-functionalized supports and the stabilized ultrasmall PdNPs. This work might open new avenues for the development of functionalized catalysts with supported ultrasmall metal nanoparticles and hybrid porous support as well as their clean catalyses.

This paper presents the development of wood flour (WF)-filled polylactic acid (PLA) composite filaments for a fused deposition modeling (FDM) process with the aim of application to 3D printing. The composite filament consists of wood flour (5 wt %) in a PLA matrix. The detailed formulation and characterization of the composite filament were investigated experimentally, including tensile properties, microstructure, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The feedstock filaments of this composite were produced and used successfully in an assembled FDM 3D printer. The research concludes that compared with pure PLA filament, adding WF changed the microstructure of material fracture surface, the initial deformation resistance of the composite was enhanced, the starting thermal degradation temperature of the composite decreased slightly, and there were no effects on the melting temperature. The WF/PLA composite filament is suitable to be printed by the FDM process.

Hydrogenation of CO2 to methanol utilizing the hydrogen from renewable energy sources offers a promising way to reduce CO2 emissions through the CO2 utilization as a carbon source. However, it is a challenge to convert CO2 to methanol with high activity and high methanol selectivity. Herein, we report a class of metal-oxide solid-solution catalysts: MaZrO x (Ma = Cd, Ga), which show a methanol selectivity up to 80% with the CO2 single pass conversion reaching 4.3%–12.4% under the reaction conditions of H2/CO2 = 3/1, 24 000 h–1, 5 MPa. Structural and electronic characterizations combined with denisty functional theory calculations suggest that the Ma and Zr components in MaZrO x (Ma = Cd, Ga) solid-solution catalysts show a strong synergetic effect, which enhances the H2 heterolytic dissociation and results in high activity and high methanol selectivity. The solid-solution catalyst with dual metal oxide components offers an approach for the selective hydrogenation of CO2 to chemicals.

Single-atom metal-nitrogen-carbon (M-N-C) catalysts have sparked intensive interests, however, the development of an atomically dispersed metal-phosphorus-carbon (M-P-C) catalyst has not been achieved, although molecular metal-phosphine complexes have found tremendous applications in homogeneous catalysis. Herein, we successfully construct graphitic phosphorus species coordinated single-atom Fe on P-doped carbon, which display outstanding catalytic performance and reaction generality in the heterogeneous hydrogenation of N-heterocycles, functionalized nitroarenes, and reductive amination reactions, while the corresponding atomically dispersed Fe atoms embedded on N-doped carbon are almost inactive under the same reaction conditions. Furthermore, we find that the catalytic activity of graphitic phosphorus coordinated single-atom Fe sharply decreased when Fe atoms were transformed to Fe clusters/nanoparticles by post-impregnation Fe species. This work can be of fundamental interest for the design of single-atom catalysts by utilizing P atoms as coordination sites as well as of practical use for the application of M-P-C catalysts in heterogeneous catalysis.

Photoelectrocatalytic (PEC) degradation of organic pollutants into CO2 and H2O is a promising strategy for addressing ever-growing environmental problems. Titanium dioxide (TiO2) has been widely studied because of its good performance and environmental benignancy; however, the PEC activity of TiO2 catalyst is substantially limited due to its fast electron–hole recombination. Herein, we report a TiO2 nanocone-based photoelectrocatalyst with superior degradation performance and outstanding durability. The unique conical catalyst can boost the PEC degradation of 4-chlorophenol (4-CP) with 99% degradation efficiency and higher than 55% mineralization efficiency at a concentration of 20 ppm. The normalized apparent rate constant of a nanocone catalyst is 5.05 h–1 g–1 m2, which is 3 times that of a nanorod catalyst and 6 times that of an aggregated particle catalyst, respectively. Further characterizations reveal that the conical morphology of TiO2 can make photogenerated charges separate and transfer more efficiently, resulting in outstanding PEC activity. Moreover, computational fluid dynamics simulations indicate that a three-dimensional conical structure is beneficial for mass transfer. This work highlights that tuning the morphology of a photoelectrocatalyst at the nanometer scale not only promotes the charge transfer but also facilitates the mass transportation, which jointly enhance the PEC performance in the degradation of persistent pollutants.