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Cobalt ferrite (CoFe2O4) spinel has been found to produce C2−C4 hydrocarbons in a single‐step, ambient‐pressure, photocatalytic hydrogenation of CO2 with a rate of 1.1 mmol g−1 h−1, selectivity of 29.8 % and conversion yield of 12.9 %. On stream the CoFe2O4 reconstructs to a CoFe−CoFe2O4 alloy‐spinel nanocomposite which facilitates the light‐assisted transformation of CO2 to CO and hydrogenation of the CO to C2−C4 hydrocarbons. Promising results obtained from a laboratory demonstrator bode well for the development of a solar hydrocarbon pilot refinery. [ABSTRACT FROM AUTHOR]

Cobalt ferrite (CoFe2O4) spinel has been found to produce C2−C4 hydrocarbons in a single‐step, ambient‐pressure, photocatalytic hydrogenation of CO2 with a rate of 1.1 mmol g−1 h−1, selectivity of 29.8 % and conversion yield of 12.9 %. On stream the CoFe2O4 reconstructs to a CoFe−CoFe2O4 alloy‐spinel nanocomposite which facilitates the light‐assisted transformation of CO2 to CO and hydrogenation of the CO to C2−C4 hydrocarbons. Promising results obtained from a laboratory demonstrator bode well for the development of a solar hydrocarbon pilot refinery. [ABSTRACT FROM AUTHOR]

Engineering sophisticated structure of Al2O3 and controlling the structure of counterpart metal active sites remain challenges to achieve a high catalytic‐performance in heterogeneous catalysis. Herein, we present a confinement strategy to stabilize homogeneous Ni by penta‐coordinated Al3+ anchoring sites in Al2O3. This approach is involved in using a metal–organic framework as host to load Ni2+ ions, by the aim of producing a confined Ni/Al2O3 catalyst after a standard calcination. Metal–support interaction between Ni and Al2O3 was tailored to be medium to avoid the formation of inactive NiAl2O4, which favors the generation of more available Ni active sites accessible to the reactants. The resultant Ni/Al2O3 exhibited superior catalytic performance in comparison with the control Ni/Al2O3 in CO methanation owing to the presence of defective sites on sufficient Ni0 surface. Furthermore, the presence of oxygen vacancies on Al2O3 and hydrogen spillover contributed toward excellent coke resistance properties in the reaction. [ABSTRACT FROM AUTHOR]

Light harvesting, separation of charge carriers, and surface reactions are three fundamental steps that are essential for an efficient photocatalyst. Here we show that these steps in the TiO2 can be boosted simultaneously by disorder engineering. A solid-state reduction reaction between sodium and TiO2 forms a core-shell c-TiO2@a-TiO2-x(OH)y heterostructure, comprised of HO-Ti-[O]-Ti surface frustrated Lewis pairs (SFLPs) embedded in an amorphous shell surrounding a crystalline core, which enables a new genre of chemical reactivity. Specifically, these SFLPs heterolytically dissociate dihydrogen at room temperature to form charge-balancing protonated hydroxyl groups and hydrides at unsaturated titanium surface sites, which display high reactivity towards CO2 reduction. This crystalline-amorphous heterostructure also boosts light absorption, charge carrier separation and transfer to SFLPs, while prolonged carrier lifetimes and photothermal heat generation further enhance reactivity. The collective results of this study motivate a general approach for catalytically generating sustainable chemicals and fuels through engineered disorder in heterogeneous CO2 photocatalysts. Developing an efficient photocatalyst for CO2 reduction is appealing. Here, the authors report a core-shell c-TiO2@a-TiO2-x(OH)y heterostructure with surface frustrated Lewis pairs on amorphous shells which enables a new genre of chemical reactivity. [ABSTRACT FROM AUTHOR]

It has long been known that the thermal catalyst Cu/ZnO/Al2O3(CZA) can enable remarkable catalytic performance towards CO2 hydrogenation for the reverse water-gas shift (RWGS) and methanol synthesis reactions. However, owing to the direct competition between these reactions, high pressure and high hydrogen concentration (≥75%) are required to shift the thermodynamic equilibrium towards methanol synthesis. Herein, a new black indium oxide with photothermal catalytic activity is successfully prepared, and it facilitates a tandem synthesis of methanol at a low hydrogen concentration (50%) and ambient pressure by directly using by-product CO as feedstock. The methanol selectivities achieve 33.24% and 49.23% at low and high hydrogen concentrations, respectively. Harsh reaction conditions are generally required for CO2 hydrogenation to shift the thermodynamic equilibrium towards methanol synthesis. Here, a new black indium oxide with two types of active sites, frustrated Lewis pairs and oxygen vacancies, is prepared, and facilitates a tandem synthesis of methanol at a low hydrogen concentration (50%) and ambient pressure. [ABSTRACT FROM AUTHOR]

Nitrogen fixation via the electrochemical nitrogen reduction reaction under ambient conditions has the potential to disrupt the energy-intensive Haber–Bosch process with a more environmentally friendly alternative. Utilizing air as the feed stock would represent an important step towards future industrialization of green ammonia. Herein, a gold–copper nanoalloy-decorated zeolitic imidazolate framework, denoted as AuCu/ZIF-8, exhibits high NH3 yield, remarkable efficiency, long-term stability and pH independence for the electrochemical synthesis of ammonia. Making ammonia from thin air and renewable electricity speaks well for the development of sustainable ammonia refineries. [ABSTRACT FROM AUTHOR]

Silicene is a relatively new member of the growing family of two-dimensional single-element materials. Both top-down and bottom-up approaches provide access to silicene, the former via vapor deposition on a substrate and the latter via exfoliation of the layered CaSi2 precursor. Most top-down research has been concerned with understanding the various electronic, optical, magnetic, mechanical, electrical, thermal transport and gas-adsorption properties of silicene. By contrast, the focus on bottom-up silicene has primarily been on its synthesis, structure and chemical properties as they relate to its function and utility. Herein, emphasis is placed on the bottom-up strategy because of its scalability and the ease of subsequent silicene modification, with both qualities being important prerequisites for heterogeneous catalysis applications. In this context, synthetic freestanding silicene exists as single sheets or multilayer assemblies, depending on the CaSi2 exfoliation synthesis conditions. The structure of a sheet comprises three connected chair-configuration silicon 6-rings. This connectivity creates buckled sheets in which the hybridization around the unsaturated silicon atoms is sp2–sp3. By adjusting the CaSi2 exfoliation synthesis conditions, either layered silane (Si6H6) or siloxene (Si6H3(OH)3) nanosheets can be obtained. In our studies, we have explored the nucleation and growth of different transition metal nanoparticles on and within the layer spaces of these nanosheets, and explored their thermochemical and photochemical reactivity in CO2 hydrogenation reactions. An overview of these findings, related works and a new-and-optimized catalyst are provided in this article. [ABSTRACT FROM AUTHOR]

Black liquor, an industrial waste product of papermaking, is primarily used as a low‐grade combustible energy source. Despite its high lignin content, the potential utility of black liquor as a feedstock in products manufacturing, remains to be exploited. Demonstrated here in is the use of black liquor as a primary feed‐stock for synthesizing graphene quantum dots that exhibit both up‐conversion and photoluminescence when excited using visible/near‐infrared radiation, thereby enabling the photosensitization of ultraviolet‐absorbing TiO2 nanosheets. In addition, these graphene quantum dots can trap photo‐generated electrons to realize the effective separation of electron‐hole pairs. Together, these two processes facilitate the solar‐powered generation of H2 from H2O, and CO from H2O–CO2, using broadband solar radiation. [ABSTRACT FROM AUTHOR]

Abstract: Frustrated Lewis pairs (FLPs) created by sterically hindered Lewis acids and Lewis bases have shown their capacity for capturing and reacting with a variety of small molecules, including H2 and CO2, and thereby creating a new strategy for CO2 reduction. Here, the photocatalytic CO2 reduction behavior of defect‐laden indium oxide (In2O3−x(OH)y) is greatly enhanced through isomorphous substitution of In3+ with Bi3+, providing fundamental insights into the catalytically active surface FLPs (i.e., InOH···In) and the experimentally observed “volcano” relationship between the CO production rate and Bi3+ substitution level. According to density functional theory calculations at the optimal Bi3+ substitution level, the 6s2 electron pair of Bi3+ hybridizes with the oxygen in the neighboring InOH Lewis base site, leading to mildly increased Lewis basicity without influencing the Lewis acidity of the nearby In Lewis acid site. Meanwhile, Bi3+ can act as an extra acid site, serving to maximize the heterolytic splitting of reactant H2, and results in a more hydridic hydride for more efficient CO2 reduction. This study demonstrates that isomorphous substitution can effectively optimize the reactivity of surface catalytic active sites in addition to influencing optoelectronic properties, affording a better understanding of the photocatalytic CO2 reduction mechanism. [ABSTRACT FROM AUTHOR]

The search for earth-abundant and high-performance electrode materials for sodium-ion batteries represents an important challenge to current battery research. 2D transition metal dichalcogenides, particularly MoS2, have attracted increasing attention recently, but few of them so far have been able to meet expectations. In this study, it is demonstrated that another phase of molybdenum sulfide-amorphous chain-like MoS3-can be a better choice as the anode material of sodium-ion batteries. Highly compact MoS3 particles infiltrated with carbon nanotubes are prepared via the facile acid precipitation method in ethylene glycol. Compared to crystalline MoS2, the resultant amorphous MoS3 not only exhibits impressive gravimetric performance-featuring excellent specific capacity (≈615 mA h g−1), rate capability (235 mA h g−1 at 20 A g−1), and cycling stability but also shows exceptional volumetric capacity of ≈1000 mA h cm−3 and an areal capacity of >6.0 mA h cm−2 at very high areal loadings of active materials (up to 12 mg cm−2). The experimental results are supported by density functional theory simulations showing that the 1D chains of MoS3 can facilitate the adsorption and diffusion of Na+ ions. At last, it is demonstrated that the MoS3 anode can be paired with an Na3V2(PO4)3 cathode to afford full cells with great capacity and cycling performance. [ABSTRACT FROM AUTHOR]

Size-independent emission has been widely observed for ultrasmall thiolated gold nanoparticles (AuNPs) but our understanding of the photoluminescence mechanisms of noble metals on the nanoscale has remained limited. Herein, we report how the emission wavelength of a AuNP and the local binding geometry of a thiolate ligand (glutathione) on the AuNP are correlated, as these AuNPs emit at different wavelengths in spite of their identical size (ca. 2.5 nm). By using circular dichroism, X-ray absorption, and fluorescence spectroscopy, we found that a high Au−S coordination number (CN) and a high surface coverage resulted in strong AuI-ligand charge transfer, a chiral conformation, and 600 nm emission, whereas a low Au−S CN and a low surface coverage led to weak charge transfer, an achiral conformation, and 810 nm emission. These two size-independent emissions can be integrated into one single 2.5 nm AuNP by fine-tuning of the surface coverage; a ratiometric pH response was then observed owing to strong energy transfer between two emission centers, opening up new possibilities for the design of ultrasmall ratiometric pH nanoindicators. [ABSTRACT FROM AUTHOR]

Stable platinum nanoparticles weresynthesized by the self-assemblyof alkene derivatives onto the platinum surface, possibly formingplatinum–vinylidene (PtCCH−) or −acetylide(Pt–C) interfacial bonds as a result of dehydrogenationand transformation of the olefin moieties catalyzed by platinum. Transmissionelectron microscopic measurements showed that the nanoparticles werewell-dispersed without apparent agglomeration, indicating effectivepassivation of the nanoparticles by the ligands, and the average corewas estimated to be 1.34 ± 0.39 nm. FTIR measurements showedthe emergence of a new vibrational band at 2023 cm–1, which was ascribed to the formation of Pt–H and CCfrom the dehydrogenation of alkene ligands on platinum surfaces. Consistentbehaviors were observed in photoluminescence measurements, where theemission profiles were similar to those of alkyne-functionalized Ptnanoparticles that arose from intraparticle charge delocalizationbetween the particle-bound acetylene moieties. Selective reactivitywith imine derivatives further confirmed the formation of PtCCH–or Pt–C interfacial linkages, as manifested in NMRand electrochemical measurements. Further structural insights wereobtained by X-ray absorption near-edge spectroscopy and extended X-rayabsorption fine structure analysis, where the coordinate numbers andbond lengths of the Pt–Pt and Pt–C linkages suggestedthat the metal–ligand interfacial bonds were in the intermediatebetween those of Pt–C and Pt–Csp2. [ABSTRACT FROM AUTHOR]

The electronic structure study of carbon nanotube–graphene complexes has been performed using comprehensive X-ray absorption spectroscopy (XAS) at Fe L- and K-edges, along with C, N and O K-edges. The results obtained from the study of an iron-containing carbon nanotube–graphene complex (NT–G) have been compared in great detail with those of an iron-free carbon nanotube–graphene complex (pNT–G) and iron phthalocyanine (FePc). It has been confirmed that complex-like Fe3+ in a high spin state is the major iron component in NT–G. The C and N K-edge XANES further confirmed that Fe is very likely to be bonded to N in NT–G. This Fe–N species should be the active site for enhanced oxygen reduction reaction (ORR) activity in NT–G. A unique O K-edge X-ray absorption spectroscopic feature has been observed in NT–G, which might be caused by chemisorbed O2 on the Fe–N site. Such knowledge is important for the understanding of this specific complex, and the knowledge should benefit the rational design of other carbon/metal/nitrogen-containing ORR catalysts with further improved performance. [ABSTRACT FROM AUTHOR]

The surface frustrated Lewis pairs (SFLPs) on defect-laden metal oxides provide catalytic sites to activate H2 and CO2 molecules and enable efficient gas-phase CO2 photocatalysis. Lattice engineering of metal oxides provides a useful strategy to tailor the reactivity of SFLPs. Herein, a one-step solvothermal synthesis is developed that enables isomorphic replacement of Lewis acidic site In3+ ions in In2O3 by single-site Bi3+ ions, thereby enhancing the propensity to activate CO2 molecules. The so-formed BixIn2-xO3 materials prove to be three orders of magnitude more photoactive for the reverse water gas shift reaction than In2O3 itself, while also exhibiting notable photoactivity towards methanol production. The increased solar absorption efficiency and efficient charge-separation and transfer of BixIn2-xO3 also contribute to the improved photocatalytic performance. These traits exemplify the opportunities that exist for atom-scale engineering in heterogeneous CO2 photocatalysis, another step towards the vision of the solar CO2 refinery. Surface frustrated Lewis pairs (SFLPs) provide a unique class of active sites that enable efficient gas-phase CO2 photocatalysis. How to tailor the reactivity of the SFLPs represents a major challenge, which the authors address here by single-site Bi3+ ion substitution of the SFLPs. [ABSTRACT FROM AUTHOR]

Die Synthese von Graphenquantenpunkten aus dem industriellen Abfallprodukt Schwarzlauge wird von W. Sun, J. Chen, G. A. Ozin et al. in der Zuschrift auf S. 14992 beschrieben. Die GQDs werden genutzt, um die photokatalytische Aktivität von TiO SB 2 sb in der H SB 2 sb O- und CO SB 2 sb -Reduktion zu steigern. [Extracted from the article]

The extraction and combustion of fossil natural gas, consisting primarily of methane, generates vast amounts of greenhouse gases that contribute to climate change. However, as a result of recent research efforts, "solar methane" can now be produced through the photocatalytic conversion of carbon dioxide and water to methane and oxygen. This approach could play an integral role in realizing a sustainable energy economy by closing the carbon cycle and enabling the efficient storage and transportation of intermittent solar energy within the chemical bonds of methane molecules. In this article, we explore the latest research and development activities involving the light-assisted conversion of carbon dioxide to methane. While natural gas and fossil fuels power human activities, increasing concerns over fuel reserves and environmental impacts require finding alternative, renewable resources. Here, authors review the fundamental science and progress on solar-powered conversion of carbon dioxide to methane. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials are of considerable interest for catalyzing the heterogeneous conversion of CO2 to synthetic fuels. In this regard, 2D siloxene nanosheets, have escaped thorough exploration, despite being composed of earth-abundant elements. Herein we demonstrate the remarkable catalytic activity, selectivity, and stability of a nickel@siloxene nanocomposite; it is found that this promising catalytic performance is highly sensitive to the location of the nickel component, being on either the interior or the exterior of adjacent siloxene nanosheets. Control over the location of nickel is achieved by employing the terminal groups of siloxene and varying the solvent used during its nucleation and growth, which ultimately determines the distinct reaction intermediates and pathways for the catalytic CO2 methanation. Significantly, a CO2 methanation rate of 100 mmol gNi−1 h−1 is achieved with over 90% selectivity when nickel resides specifically between the sheets of siloxene. There is a strong push to develop new catalysts and supports to convert low-value CO2 into high-value CH4. Here, authors found that the internal or external confinement of Ni on multi-layered siloxene supports determined the reaction pathway, activity, selectivity, and stability in CO2 methanation. [ABSTRACT FROM AUTHOR]

This work aims to provide an overview of producing value‐added products affordably and sustainably from greenhouse gases (GHGs). Methanol (MeOH) is one such product, and is one of the most widely used chemicals, employed as a feedstock for ≈30% of industrial chemicals. The starting materials are analogous to those feeding natural processes: water, CO2, and light. Innovative technologies from this effort have global significance, as they allow GHG recycling, while providing society with a renewable carbon feedstock. Light, in the form of solar energy, assists the production process in some capacity. Various solar strategies of continually increasing technology readiness levels are compared to the commercial MeOH process, which uses a syngas feed derived from natural gas. These strategies include several key technologies, including solar‐thermochemical, photochemical, and photovoltaic–electrochemical. Other solar‐assisted technologies that are not yet commercial‐ready are also discussed. The commercial‐ready technologies are compared using a technoeconomic analysis, and the scalability of solar reactors is also discussed in the context of light‐incorporating catalyst architectures and designs. Finally, how MeOH compares against other prospective products is briefly discussed, as well as the viability of the most promising solar MeOH strategy in an international context. [ABSTRACT FROM AUTHOR]