Co0 -Coδ+ Interface Double-Site-Mediated C-C Coupling for the Photothermal Conversion of CO2 into Light Olefins.

Solar-driven CO2 hydrogenation into multi-carbon products is a highly desirable, but challenging reaction. The bottleneck of this reaction lies in the C-C coupling of C1 intermediates. Herein, we construct the C-C coupling centre for C1 intermediates via the in situ formation of Co0 -Coδ+ interface double sites on MgAl2 O4 (Co-CoOx /MAO). Our experimental and theoretical prediction results confirmed the effective adsorption and activation of CO2 by the Co0 site to produce C1 intermediates, while the introduction of the electron-deficient state of Coδ+ can effectively reduce the energy barrier of the key CHCH* intermediates. Consequently, Co-CoOx /MAO exhibited a high C2-4 hydrocarbons production rate of 1303 µmol g-1 h-1 ; the total organic carbon selectivity of C2-4 hydrocarbons is 62.5 % under light irradiation with a high ratio (≈11) of olefin to paraffin. This study provides a new approach toward the design of photocatalysts used for CO2 conversion into C2+ products.

Elemental Boron for Efficient Carbon Dioxide Reduction under Light Irradiation.

The photoreduction of CO2 is attractive for the production of renewable fuels and the mitigation of global warming. Herein, we report an efficient method for CO2 reduction over elemental boron catalysts in the presence of only water and light irradiation through a photothermocatalytic process. Owing to its high solar-light absorption and effective photothermal conversion, the illuminated boron catalyst experiences remarkable self-heating. This process favors CO2 activation and also induces localized boron hydrolysis to in situ produce H2 as an active proton source and electron donor for CO2 reduction as well as boron oxides as promoters of CO2 adsorption. These synergistic effects, in combination with the unique catalytic properties of boron, are proposed to account for the efficiency of the CO2 reduction. This study highlights the promise of photothermocatalytic strategies for CO2 conversion and also opens new avenues towards the development of related solar-energy utilization schemes.

Optimization of Photothermal Catalytic Reaction of Ethyl Acetate and NO Catalyzed by Biochar-Supported MnOx-TiO2 Catalysts.

The substitution of ethyl acetate for ammonia in NH3-SCR provides a novel strategy for the simultaneous removal of VOCs and NO. In this study, three distinct types of biochar were fabricated through pyrolysis at 700 °C. MnOx and TiO2 were sequentially loaded onto these biochar substrates via a hydrothermal process, yielding a family of biochar-based catalysts with optimized dosages. Upon exposure to xenon lamp irradiation at 240 °C, the biochar catalyst designated as 700-12-3GN, derived from Ginkgo shells, demonstrated the highest catalytic activity when contrasted with its counterparts prepared from moso bamboo and loofah. The conversion efficiencies for NO and ethyl acetate (EA) peaked at 73.66% and 62.09%, respectively, at a catalyst loading of 300 mg. The characterization results indicate that the 700-12-3GN catalyst exhibits superior activity, which can be attributed to the higher concentration of Mn4+ and Ti4+ species, along with its superior redox properties and suitable elemental distribution. Notably, the 700-12-3GN catalyst has the smallest specific surface area but the largest pore volume and average BJH pore size, indicating that the specific surface area is not the predominant factor affecting catalyst performance. Instead, pore volume and average BJH pore diameter appear to be the more influential parameters. This research provides a reference and prospect for the resource utilization of biochar and the development of photothermal co-catalytic ethyl acetate and NO at low cost.

Efficient solar-driven CO2-to-fuel conversion via Ni/MgAlO x @SiO2 nanocomposites at low temperature.

Solar-driven CO2-to-fuel conversion assisted by another major greenhouse gas CH4 is promising to concurrently tackle energy shortage and global warming problems. However, current techniques still suffer from drawbacks of low efficiency, poor stability, and low selectivity. Here, a novel nanocomposite composed of interconnected Ni/MgAlO x nanoflakes grown on SiO2 particles with excellent spatial confinement of active sites is proposed for direct solar-driven CO2-to-fuel conversion. An ultrahigh light-to-fuel efficiency up to 35.7%, high production rates of H2 (136.6 mmol min-1g- 1) and CO (148.2 mmol min-1g-1), excellent selectivity (H2/CO ratio of 0.92), and good stability are reported simultaneously. These outstanding performances are attributed to strong metal-support interactions, improved CO2 absorption and activation, and decreased apparent activation energy under direct light illumination. MgAlO x @SiO2 support helps to lower the activation energy of CH* oxidation to CHO* and improve the dissociation of CH4 to CH3* as confirmed by DFT calculations. Moreover, the lattice oxygen of MgAlO x participates in the reaction and contributes to the removal of carbon deposition. This work provides promising routes for the conversion of greenhouse gasses into industrially valuable syngas with high efficiency, high selectivity, and benign sustainability.

Controllable synthesis various morphologies of 3D hierarchical MnOx-TiO2 nanocatalysts for photothermocatalysis toluene and NO with free-ammonia.

Via various hydrothermal synthetic conditions, controllable synthesis various morphologies of MnOx-TiO2 catalysts for simultaneous removal toluene and NO with free-ammonia under the photothermocatalysis system based on UV light irradiation. The morphologies obtained included 3D hierarchical sheet structure (C sample), 3D hierarchical sheet stacked MnOx-TiO2 microspheres (P sample), and 3D hierarchical sticks stacked MnOx-TiO2 microspheres (N sample). Compared with other samples, N sample exhibited the excellent catalytic activity for the toluene and NO, with the conversion rates of toluene and NO achieved 72% and 91% at 240 °C, respectively. Using a variety of characterization and analysis methods, it was confirmed that the morphology of the catalysts would affect its catalytic performance by affecting the specific surface area, surface-adsorbed oxygen species, oxygen vacancies, the high-valence atomic species and reducibility. This was the reason why the N sample could show remarkable performance. Moreover, this work demonstrated a new strategy for simultaneously removing toluene and NO with free-ammonia under the photothermocatalysis system based on UV light irradiation.

Polydopamine mediated modification of manganese oxide on melamine sponge for photothermocatalysis of gaseous formaldehyde.

It is an urgent need to develop environmentally friendly strategies with low energy consumption for gaseous formaldehyde (HCHO) purification. Herein, a sponge based MS/PDA/MnOx catalyst with plentiful 3D porosities was constructed. The dual-functional PDA layer not only promoted the MnOx loading (25 wt% MnOx in the composite), but also acted as a photothermal converter to absorb photo-irradiation to heat MnOx catalyst (~80 °C after 10 min irradiation). Moreover, the 3D network structure favored the mass transfer and effectively reduced the catalyst agglomeration to expose more active sites. As a result, the obtained MS/PDA/MnOx photothermocatalyst showed highly efficient performance for removal of HCHO within concentration of 40-320 ppm at room temperature under xenon light irradiation. This process followed a pseudo-second-order model, and the reaction rate of the MS/PDA/MnOx was 4.82 times of the MS/MnOx. Finally, a possible photothermocatalysis mechanism was proposed based on the intermediate examination via the in-situ DRIFTS investigation.

Enhanced light-driven photothermocatalytic activity on selectively dissolved LaTi1-xMnxO3+δ perovskites by photoactivation.

LaTi1-xMnxO3+δ (x = 0.2 and 0.4) perovskite-type catalysts are synthesized by acrylamide polymerization route and etched with diluted HNO3 for oxidation of toluene as one of typical volatile organic compounds (VOCs). The substitution of Mn cations improves catalytic activity (toluene conversion increased from 0 to 50.6% by substituting 40% of Ti cations with Mn cations) by improving abilities of light absorption and light-to-heat conversion, and acid etching further promotes catalytic activity (toluene conversion increased from 50.6%-95.6% for LaTi0.6Mn0.4O3+δ) by enlarging specific surface area, generating more surface active oxygen, strengthening mobility of surface oxygen, and improving low-temperature reducibility. To explore the origin of the light-driven photothermocatalytic activity of A-LaTi0.6Mn0.4O3+δ by EPR analysis, O2 desorption and H2 consumption, we find that the light is not only as a thermal source to provide energy for toluene oxidation but also can promote oxidation reaction by photoactivation.

Photoinduced Defect Engineering: Enhanced Photothermal Catalytic Performance of 2D Black In2 O3- x Nanosheets with Bifunctional Oxygen Vacancies.

Photothermal CO2 reduction technology has attracted tremendous interest as a solution for the greenhouse effect and energy crisis, and thereby it plays a critical role in solving environmental problems and generating economic benefits. In2 O3- x has emerged as a potential photothermal catalyst for CO2 conversion into CO via the light-driven reverse water gas shift reaction. However, it is still a challenge to modulate the structural and electronic characteristics of In2 O3 to enhance photothermocatalytic activity synergistically. In this work, a novel route to activate inert In(OH)3 into 2D black In2 O3- x nanosheets via photoinduced defect engineering is proposed. Theoretical calculations and experimental results verify the existence of bifunctional oxygen vacancies in the 2D black In2 O3- x nanosheets host, which enhances light harvesting and chemical adsorption of CO2 molecules dramatically, achieving 103.21 mmol gcat -1 h-1 with near-unity selectivity for CO generation and meanwhile excellent stability. This study reveals an exciting phenomenon that light is an ideal external stimulus on the layered In2 O3 system, and its electronic structure can be adjusted efficiently through photoinduced defect engineering; it can be anticipated that this synthesis strategy can be extended to wider application fields.