Symmetry Breaking Induced Amorphization of Cobalt-Based Catalyst for Boosted CO2 Photoreduction.

Photocatalytic reduction of CO2 to energy carriers is intriguing in the industry but kinetically hard to fulfil due to the lack of rationally designed catalysts. A promising way to improve the efficiency and selectivity of such reduction is to break the structural symmetry of catalysts by manipulating coordination. Here, inspired by analogous CoO6 and CoSe6 octahedral structural motifs of the Co(OH)2 and CoSe, a hetero-anionic coordination strategy is proposed to construct a symmetry-breaking photocatalyst prototype of oxygen-deficient Se-doped cobalt hydroxide upon first-principles calculations. Such involvement of large-size Se atoms in CoO6 octahedral frameworks experimentally lead to the switching of semiconductor type of cobalt hydroxide from p to n, generation of oxygen defects, and amorphization. The resultant oxygen-deficient Se,O-coordinated Co-based amorphous nanosheets exhibit impressive photocatalytic performance of CO2 to CO with a generation rate of 60.7 µmol g-1 h-1 in the absence of photosensitizer and scavenger, superior to most of the Co-based photocatalysts. This work establishes a correlation between the symmetry-breaking of catalytic sites and CO2 photoreduction performances, opening up a new paradigm in the design of amorphous photocatalysts for CO2 reduction.

Rich oxygen vacancies in confined heterostructured TiO2@In2S3 hybrid for boosting solar-driven CO2 reduction.

Solar energy driving CO2 reduction is a potential strategy that not only mitigates the greenhouse effect caused by high CO2 level in atmosphere, but also yields carbon chemicals/fuels at the same time. Herein, a facile way to design the heterogeneous TiO2@In2S3 hollow structures possessing robust light harvesting in both ultraviolet and visible regions is proposed and exhibits a higher generation rate of 25.35 and 1.24 µmol·g-1·h-1 for photocatalytic CO2 reduction to CO and CH4, respectively. The excellent photocatalytic catalytic performance comes from i) the confined heterostructured TiO2@In2S3 possesses a suitable band structure and a broadband-light absorbing capacity for CO2 photoreduction, ii) the rich interfaces between nanosized TiO2 and In2S3 on the shell can significantly reduce the diffusion length of carriers and enhance the utilization efficiency of photogenerated electron-hole pairs, and iii) enriched surface oxygen vacancies can provide more active sites for CO2 adsorption.

In situ generated gas bubble-directed self-assembly of multifunctional MgO-based hybrid foams for highly efficient thermal conduction, microwave absorption, and self-cleaning.

Developing multifunctional materials with superior thermal conductivity and microwave absorption is an effective means to address the increasingly serious electromagnetic (EM) compatibility and heat dissipation problems in modern electron devices. Here, multifunctional MgO/Mg(OH)2/C, MgO/M/C (M = Co, Ni, Cu), and MgO/NOx/C (N = Fe, Mn) hybrid foams were synthesized using a facile one-step gas-bubble-assisted combustion method, and their texture, composition, and properties were regulated by tuning salt type and feeding ratio. Our results show that the MgO/Co/C foams have high thermal conductivity (3.40-4.09 W m-1 K-1) with a filler load of 20-50 wt% at the Co2+ molar content of φ = 70 mol% and excellent EM wave absorption (EABW = 11.44 GHz), with a thickness of 2.1 mm and a minimal reflection loss of -59.42 dB at φ = 90 mol%. The enhanced properties are ascribed to the construction of foams with 3D interconnected networks and the synergistic effect of magnetic Co, insulating MgO, and dielectric C, which provide a continuous pathway for electron/phonon relay transmission and magnetic/dielectric dual losses. Moreover, the MgO/Co/C foams possess strong mechanical/hydrophobicity performance, tunable magnetic properties, and electrical conductivity, and can be applied in self-cleaning, electromagnetic interference, and heat management. Overall, this study offers a novel understanding of preparing multifunctional heat conductive-EM wave absorptive foam materials in modern electronic devices.

Lattice Distortion in a Confined Structured ZnS/ZnO Heterojunction for Efficient Photocatalytic CO2 Reduction.

It is a promising strategy to effectively promote "carbon neutrality" by reducing CO2 to small energy molecules through photocatalysis technology. However, due to low light utilization and recombination of photogenerated carriers, photocatalysts usually have low activity and low selectivity for products. Herein, a hollow spherical ZnS/ZnO heterojunction with a spatial confinement effect photocatalyst was synthesized toward CO2 photoreduction through preciously controlling the nano-/microstructure. The local lattice distortions were introduced into the surface of the hollow ZnS/ZnO microsphere, which activated lattice oxygen and provided additional active reaction sites. Furthermore, the heterojunction constructed between ZnS and ZnO interfaces facilitated the separation of photoinduced charge carriers. Combined with the natural advantage of enhanced light capture and absorption for a hollow confined structure, as a result, the systemic design in the electronic and confined structures for the photocatalyst has brought an excellent CO2 reduction performance with a CO yield rate as high as 35.85 µmol g-1h-1 and durability under a 300 W Xe lamp irradiation without any sacrificial agent and cocatalyst.

Urchin-like band-matched Fe2O3@In2S3 hybrid as an efficient photocatalyst for CO2 reduction.

Herein, an urchin-like Fe2O3@In2S3 hybrid composite is designed and synthesized using a facile process. The composite efficiently harvests light in both the ultraviolet and visible regions, and the unique hierarchical structure provides several advantages for photocatalytic applications: (i) a suitable band-matching structure and broadband-light absorbing capacity enable the reduction of CO2 into hydrocarbon, (ii) the extensive network of interfacial contact between nano-sized Fe2O3 and In2S3 significantly increases the separation of charge carriers and enhances the utilization of photogenerated electron-hole pairs, and (iii) an abundance of surface oxygen vacancies provide numerous active sites for CO2 molecule adsorption. The optimized Fe2O3@In2S3 composite generated CO from the photocatalytic reduction of CO2 at a rate of 42.83 µmol·g-1·h-1, and no signs of deactivation were observed during continued testing for 32 h under 300 W Xe lamp irradiation.

Synchronously boosting microwave-absorbing and heat-conducting capabilities in CeO2/Ce(OH)3 core-shell nanorods/nanofibers via Fe-doping amount control.

To address the electromagnetic interference (EMI) and heat dissipation issues in electronics, we pioneered the synthesis of Fe-doped CeO2/Ce(OH)3 core-shell nanorods/nanofibers (CSNRs/NFs) through a simple one-pot hydrothermal reaction. The growth of core-shell nanofibers was driven by the minimal surface free energy and vacancy formation energy. By controlling the amount of Fe-doping, not simply Fe0 content, crystallite size, defects, impurities, and length/diameter ratios could be modulated, but the electric, magnetic, thermal, and microwave absorption performance. The efficient 3D network constructed by 1D nanofibers in a silicone matrix offered a continuous pathway for electrons/phonon relay transmission, endowing the composites with exceptional heating conductance (3.442 W m-1 K-1) at 20%Fe-doping. An ultrawide absorption band (9.26 GHz) with intense absorption (-42.33 dB) and small thickness (1.7 mm) was achieved at 10%Fe-doping due to excellent matching performance, strong attenuation ability, and large EM parameters. Overall, Fe-doped CeO2/Ce(OH)3 CSNFs are a promising material for next-generation electronics with effective heat dissipation and EM wave absorption due to their straightforward process, mass production, and outstanding comprehensive performance. Beyond providing a deeper insight into the accurate defect modulation in magnetic-dielectric-double-loss absorbents by doping, this paper proposes an electron/phonon relay transmission strategy to improve heat conductance.

Construction of a flower-like SnS2/SnO2 junction for efficient photocatalytic CO2 reduction.

Photoreduction of CO2 to value-added chemicals and fuels is an attractive solution to alleviate environmental problems and energy crisis at the same time. However, engineering efficient photocatalysts with high activity and product selectivity is still challenging. Herein, we achieved three-dimensional (3D) spatial configuration design at micro-scale and heterogeneous interface construction at nano-scale on a SnS2/SnO2 composite, which featured hierarchical flower-like morphology consisted of nanosheets and type-II semiconductor structure. It behaved excellent selectivity and impressive photocatalytic CO2-to-CO performance with a yielding rate of 60.85 µmol g-1h-1, roughly 3 times higher than that of SnS2 and was in the front rank of this kind catalysts under 300 W Xe lamp illumination without using any sensitizers or noble metals. The enhanced catalytic capability could be attributed to the elaborately built structure with suitable energetic position that afforded effective separation and migration of photo-generated electron/hole pairs as well as enhanced light caption and absorption. Meanwhile, main reactive intermediates (e.g., CO2- and *COOH) were captured by in-situ Fourier transform infrared spectroscopy (FTIR), suggesting a fluent catalytic pathway on the SnS2/SnO2 platform. This work provides a new scheme to build advanced catalysts based on multiscale design and rational phase assembling.

Heterogeneous Hollow Multi-Shelled Structures with Amorphous-Crystalline Outer-Shells for Sequential Photoreduction of CO2.

Constructing delicate nano-/microreactors with tandem active sites in hierarchical architectures is a promising strategy for designing photocatalysts to realize the challenging but attractive CO2 reduction. Herein, hollow multi-shelled structure (HoMS) based microreactors with spatial ordered hetero-shells are fabricated, which achieve two-step CO2 -to-CH4 photoreduction. The multiple inner CeO2 shells increase the number of active catalytic sites to ensure efficient first-step reaction for generating CO, along with enriching the local CO concentration. The second-step CO-to-CH4 reaction is consequently induced by amorphous TiO2 (A-TiO2 ) composites on the adjacent outer-most shell, thus realizing the CO2 -to-CH4 conversion capability using one CeO2 @CeO2 /A-TiO2 HoMS. In-depth explorations in the microreactors provide compositional, structural, and interfacial guidance for engineering HoMS-based microreactors with temporally-spatially ordered shells toward efficient tandem catalysis.

Fiber-like ZnO with highly dispersed Pt nanoparticles for enhanced photocatalytic CO2 reduction.

Utilizing solar energy to convert carbon dioxide (CO2) into chemical fuels could simultaneously mitigate the greenhouse effect and fossil fuel crisis. Herein, a heterogeneous photocatalyst of ZnO nanofiber deposited by Pt nanoparticles was successfully synthesized toward photocatalytic CO2 reduction via radio-frequency thermal plasma and photo-deposition method. The Pt nanoparticles were introduced on the surface of ZnO nanofibers to broaden the light absorption and utilization, increase the additional reaction active sites and facilitate the separation of photo-generated electron/hole pairs. Combined with the natural advantages of short transfer path of charge carriers and self-support effecting in humid reaction environment for nanofibers, the Pt/ZnO hetero-junction nanocomposites displayed superior photocatalytic activity for CO2 reduction with respect to bare ZnO nanofibers, affording a CO-production rate as high as 45.76 µmol g-1 h-1 under 300 W Xe lamp irradiation within a gas-solid reaction system. Furthermore, in-suit Fourier transform infrared (FTIR) spectra were applied to unveil the details during photocatalytic CO2 reduction. This work presents a hetero-junction nanocomposite photocatalyst based on eco-friendly semiconductor and metal materials.

SnS2 with Flower-like Structure for Efficient CO2 Photoreduction under Visible-Light Irradiation.

Photocatalytic CO2 reduction using solar energy is a promising way to obtain renewable-energy sources for replacing fossil fuels. Through a hydrothermal process, we successfully designed and synthesized three-dimensional (3D) flower-like structured SnS2 with a sheet-like structured quasi-hexagon as the building block. The 3D hierarchical structure is conducive to light capture and absorption, the sheet structure can shorten the transmission path and promote separation of the carriers, and the self-supporting effect can effectively prevent catalyst agglomeration during the catalytic reaction. Therefore, when used in photocatalytic CO2 reduction, SnS2 with a flower-like structure showed excellent photocatalytic performance compared with SnS2 nanoparticles (NPs) under visible-light irradiation with a gas-solid reaction system.

Steering Hollow Multishelled Structures in Photocatalysis: Optimizing Surface and Mass Transport.

Hollow multishelled structures (HoMSs) provide a promising platform for fabricating photocatalysts, because the unique structure optimizes the effective surface and mass transport, showing enhanced light absorption, optimized mass transport and highly effective active sites exposed. Subsequently, the rational design on HoMS photocatalytsts is elaborated to boost the photocatalytic activity with efforts in all dimensions, from nanoscale to microscale. Breakthroughs in synthetic methodology of HoMSs have greatly evoked the prosperous photocatalytic researches for HoMSs since the developing of sequential templating approach in 2009. The dawn of HoMS photocatalyst is coming after revealing the temporal-spatial ordering property, which is also discussed in this paper with pioneer works demonstrating the greatly enhanced energy/mass transfer processes. Some insights into the key challenges and perspectives of HoMSs photocatalysts are also discussed. With the reviewed fate and future of HoMSs photocatalysts, hopefully new concepts and innovative works can be inspired to flourish this sun-rise field.

Lattice Distortion in Hollow Multi-Shelled Structures for Efficient Visible-Light CO2 Reduction with a SnS2 /SnO2 Junction.

Precise control of the micro-/nanostructures of nanomaterials, such as hollow multi-shelled structures (HoMSs), has shown its great advantages in various applications. Now, the crystal structure of building blocks of HoMSs are controlled by introducing the lattice distortion in HoMSs, for the first time. The lattice distortion located at the nanoscale interface of SnS2 /SnO2 can provide additional active sites, which not only provide the catalytic activity under visible light but also improve the separation of photoexcited electron-hole pairs. Combined with the efficient light utilization, the natural advantage of HoMSs, a record catalytic activity was achieved in solid-gas system for CO2 reduction, with an excellent stability and 100 % CO selectivity without using any sensitizers or noble metals.