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Herein is developed a ternary heterostructured catalyst, based on a periodic array of 1D TiN nanotubes, with a TiO2 nanoparticulate intermediate layer and a In2O3-x(OH)y nanoparticulate shell for improved performance in the photocatalytic reverse water gas shift reaction. It is demonstrated that the ordering of the three components in the heterostructure sensitively determine its activity in CO2 photocatalysis. Specifically, TiN nanotubes not only provide a photothermal driving force for the photocatalytic reaction, owing to their strong optical absorption properties, but they also serve as a crucial scaffold for minimizing the required quantity of In2O3-x(OH)y nanoparticles, leading to an enhanced CO production rate. Simultaneously, the TiO2 nanoparticle layer supplies photogenerated electrons and holes that are transferred to active sites on In2O3-x(OH)y nanoparticles and participate in the reactions occurring at the catalyst surface.

Catalytic reduction of carbon dioxide is a promising strategy for mitigating global carbon emissions. In particular, the abundant and nontoxic material hydroxyapatite demonstrates high activity at ...

Turanite, Cu5(VO4)2(OH)4, is a naturally occurring mineral whose physical and chemical properties are of interest for magnetic data storage, battery applications, and catalysis. In this study, the ...

Nanostructured forms of stoichiometric In2O3 are proving to be efficacious catalysts for the gas-phase hydrogenation of CO2. These conversions can be facilitated using either heat or light; however, until now, the limited optical absorption intensity evidenced by the pale-yellow color of In2O3 has prevented the use of both together. To take advantage of the heat and light content of solar energy, it would be advantageous to make indium oxide black. Herein, we present a synthetic route to tune the color of In2O3 to pitch black by controlling its degree of non-stoichiometry. Black indium oxide comprises amorphous non-stoichiometric domains of In2O3-x on a core of crystalline stoichiometric In2O3, and has 100% selectivity towards the hydrogenation of CO2 to CO with a turnover frequency of 2.44 s−1., The utilization of white-colored, wide-bandgap CO2 hydrogenation photocatalysts has been hindered by their limited light-harvesting ability. By making stoichiometric white indium oxide non-stoichiometric and black, it is transformed from a highly inactive to a highly active photothermal catalyst.

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 TiO

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.

Heterogeneous catalysis, a process in which the reaction of gaseous or liquid chemical reagents is facilitated at the surface of a solid material, is responsible for the majority of industrial-scale chemical and fuel production reactions. The energy required to drive these reactions has historically been derived from the combustion of non-renewable fossil fuels and carries an unavoidably large carbon footprint. More recently, the development of environmentally responsible and sustainable chemical industries is increasingly motivated by greenhouse gas-induced climate change, thus creating demand for eco-friendly heterogeneous catalytic processes. This includes innovative approaches enabled by renewable forms of energy, such as the electrification of chemical and petrochemical processes, utilization of CO2 as a feedstock and the incorporation of light into catalytic reactions. Herein we review the conversion of solar energy to chemical energy using CO2, and describe how the photophysical and photochemical properties of nanostructured metal oxide photocatalysts have been engineered to efficiently incorporate light into heterogeneous gas–solid CO2 hydrogenation reactions. Realizing high photonic and energy efficiencies in these systems has demanded innovation in not only photocatalyst engineering, but also photoreactor and process engineering. Rather than exclusively providing an in-depth discussion of the chemistry and science within each individual study, this Tutorial Review highlights the multidisciplinary character of photocatalysis studies by covering the four essential components of a typical research work in this field (materials engineering, theoretical modelling, reactor engineering and process development) via case studies of the archetypal indium oxide catalyst materials. Through advances in these four components, progress has been made towards the ultimate goal of industrializing the production of CO2-derived chemicals and fuels.

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.

Nanowire hydrogen bronzes of WO3 nanowires decorated with Pd (Pd/HyWO3–x) were previously demonstrated to effectively capture broadband radiation across the ultraviolet to near-infrared wavelength ...

Cuprous oxide (Cu2O), an earth-abundant, low-cost metal-oxide semiconductor, has received enormous attention for its CO2 reduction ability in aqueous media by photochemical, photoelectrochemical and electrochemical methods. An unresolved problem with all of these approaches, however, is the instability of the Cu2O caused by its tendency to undergo an irreversible redox disproportionation reaction. Here, we report a way to circumvent this troublesome behaviour of Cu2O by driving the CO2 reduction in the gas-phase via heterogeneous photocatalytic hydrogenation. To this end, Cu2O nanocubes with surfaces comprising mixed oxidation-state copper Cu(0,I,II) sites, oxygen vacancies [O] and hydroxyl OH groups were synthesized. These surfaces enable heterolysis of H2 and adsorption of CO2 under mild conditions; they facilitate the reverse water–gas shift reaction, while rendering the redox disproportionation reaction reversible. This synergism provides Cu2O nanocubes with high photocatalytic activity and stability. Cu2O is a promising photocatalyst, although its stability is compromised by a disproportionation reaction that leads to the formation of Cu and CuO. Now, a method is reported to stabilize Cu2O nanocubes, rendering them highly active and stable for the photocatalytic reverse water–gas shift reaction.

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 H2 O, and CO from H2 O-CO2 , using broadband solar radiation.

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.

It has long been known that the thermal catalyst Cu/ZnO/Al

Herein is developed a ternary heterostructured catalyst, based on a periodic array of 1D TiN nanotubes, with a TiO

Nanoscale titanium nitride TiN is a metallic material that can effectively harvest sunlight over a broad spectral range and produce high local temperatures via the photothermal effect. Nanoscale indium oxide-hydroxide, In

Photothermal catalysis is an emerging sub-discipline of heterogeneous catalysis. It is distinct from both thermochemical catalysis driven by heat and photochemical catalysis powered by sunlight. Instead, photothermal catalysis exploits broad absorption of the solar spectrum to stimulate a combination of thermochemical and photochemical processes, which contribute synergistically to driving catalytic reactions. In particular, it is proving an effective and promising strategy for converting CO2 to synthetic fuels. This article provides a critical appraisal of the concepts and principles underpinning the theory and practice of photothermal CO2 catalysis. Ultimately, the goal is to gain an appreciation of the scientific, technological, economic, and environmental challenges inevitably confronted by those pursuing the development of photothermal CO2 refineries.

1D silicon-based nanomaterials, renowned for their unique chemical and physical properties, have enabled the development of numerous advanced materials and biomedical technologies. Their production often necessitates complex and expensive equipment, requires hazardous precursors and demanding experimental conditions, and involves lengthy processes. Herein, a flash solid-solid (FSS) process is presented for the synthesis of silicon oxide nanorods completed within seconds. The innovative features of this FSS process include its simplicity, speed, and exclusive use of solid precursors, comprising hydrogen-terminated silicon nanosheets and a metal nitrate catalyst. Advanced electron microscopy and X-ray spectroscopy analyses favor a solid-liquid-solid reaction pathway for the growth of the silicon oxide nanorods with vapor-liquid-solid characteristics.

Bimetallic nanoparticles with tailored structures constitute a desirable model system for catalysts, as crucial factors such as geometric and electronic effects can be readily controlled by tailoring the structure and alloy bonding of the catalytic site. Here we report a facile colloidal method to prepare a series of platinum–gold (PtAu) nanoparticles with tailored surface structures and particle diameters on the order of 7 nm. Samples with low Pt content, particularly Pt4Au96, exhibited unprecedented electrocatalytic activity for the oxidation of formic acid. A high forward current density of 3.77 A mgPt−1 was observed for Pt4Au96, a value two orders of magnitude greater than those observed for core–shell structured Pt78Au22 and a commercial Pt nanocatalyst. Extensive structural characterization and theoretical density functional theory simulations of the best-performing catalysts revealed densely packed single-atom Pt surface sites surrounded by Au atoms, which suggests that their superior catalytic activity and selectivity could be attributed to the unique structural and alloy-bonding properties of these single-atomic-site catalysts. Bimetallic nanoparticles with tailored structure constitute a desirable model system for catalysts. PtAu nanoparticles with Pt single-atom surface sites, prepared by a colloidal method, exhibit unprecedented electrocatalytic activity for formic acid oxidation.

We report in this article a detailed study on how to stabilize a first-row transition metal (M) in an intermetallic L10-MPt alloy nanoparticle (NP) structure and how to surround the L10-MPt with an atomic layer of Pt to enhance the electrocatalysis of Pt for oxygen reduction reaction (ORR) in fuel cell operation conditions. Using 8 nm FePt NPs as an example, we demonstrate that Fe can be stabilized more efficiently in a core/shell structured L10-FePt/Pt with a 5 A Pt shell. The presence of Fe in the alloy core induces the desired compression of the thin Pt shell, especially the two atomic layers of Pt shell, further improving the ORR catalysis. This leads to much enhanced Pt catalysis for ORR in 0.1 M HClO4 solution (at both room temperature and 60 °C) and in the membrane electrode assembly (MEA) at 80 °C. The L10-FePt/Pt catalyst has a mass activity of 0.7 A/mgPt from the half-cell ORR test and shows no obvious mass activity loss after 30 000 potential cycles between 0.6 and 0.95 V at 80 °C in the MEA, m...

Synergistic effect in alloys and plasmonic effect have both been explored for increasing the efficiency of water splitting. In depth understanding and comparison of their respective contributions in certain promising systems is highly desired for catalyst development, yet rarely investigated so far. We report herein our thorough investigations on a series of highly interesting nanocomposites composed of Pt, Au and C 3 N 4 nanocomponents, which are designed to benefit from both synergistic and plasmonic effects. Detailed analyses led to an important conclusion that the contribution from the synergistic effect was at least 3.5 times that from the plasmonic effect in the best performing sample, Pt 50 Au 50 alloy decorated C 3 N 4. It showed remarkable turnover frequency of >1.6 mmol h −1 g −1 at room temperature. Our work provides physical insights for catalyst development by rationally designing samples to compare long-known synergistic effect with recently emerging, attractive plasmonic effect and represents the first case study in the field.

We synthesize a new type of hybrid Pd/WO2.72 structure with 5 nm Pd nanoparticles (NPs) anchored on 50 × 5 nm WO2.72 nanorods. The strong Pd/WO2.72 coupling results in the lattice expansion of Pd from 0.23 to 0.27 nm and the decrease of Pd surface electron density. As a result, the Pd/WO2.72 shows much enhanced catalysis toward electrochemical oxidation of formic acid in 0.1 M HClO4; it has a mass activity of ∼1600 mA/mgPd in a broad potential range of 0.4–0.85 V (vs RHE) and shows no obvious activity loss after a 12 h chronoamperometry test at 0.4 V. Our work demonstrates an important strategy to enhance Pd NP catalyst efficiency for energy conversion reactions.

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.

The catalytic oxidation of carbon monoxide to carbon dioxide by gold nanoclusters loaded onto cerium oxide supports is an important reaction that has been increasingly tailored for use in hydrogen fuel cells. It has been known that there are simultaneous mechanisms that involve coordination of both the dioxygen and carbon monoxide to the gold, as well as one in which the dioxygen is contributed in the form of lattice oxygen while the gold still coordinates the carbon monoxide. The latter has been shown to be the more potent, and it is for this reason that modulating the cerium oxide support is of vital interest. The present work provides compelling evidence that the rate-limiting step in this process is the coordination of the lattice oxygen. Exploratory studies of the control or this step via doping the cerium oxide support are also presented.

Earlier research has been primarily focused on WC as one of the most promising earth-abundant electrocatalysts for hydrogen evolution reaction (HER), whereas the other compound in this carbide family—W2C—has received far less attention. Our theoretical calculations suggest that such a focus is misplaced and W2C is potentially more HER-active than WC. Nevertheless, the preparation of phase pure and sintering-free W2C nanostructures represents a formidable challenge. Here we develop an improved carburization method and successfully prepare ultrasmall and phase-pure W2C nanoparticles. When evaluated for HER electrocatalysis, W2C nanoparticles exhibit a small onset overpotential of 50 mV, a Tafel slope of 45 mV dec−1 and outstanding long-term cycling stability, which are dramatically improved over all existing WC-based materials. In addition, the integration of W2C nanoparticles with p-type Si nanowires enables highly active and sustainable solar-driven hydrogen production. Our results highlight the great potential of this traditionally non-popular material in HER electrocatalysis. Tungsten carbide has yet to live up to its long-believed potential as a replacement for precious metal electrocatalysts. Here, Li and co-workers demonstrate that ditungsten carbide in the form of ultrasmall, phase-pure nanoparticles is a better candidate for the hydrogen evolution reaction.

Nanoscale titanium nitride TiN is a metallic material that can effectively harvest sunlight over a broad spectral range and produce high local temperatures via the photothermal effect. Nanoscale indium oxide-hydroxide, In2 O3- x (OH)y , is a semiconducting material capable of photocatalyzing the hydrogenation of gaseous CO2 ; however, its wide electronic bandgap limits its absorption of photons to the ultraviolet region of the solar spectrum. Herein, the benefits of both nanomaterials in a ternary heterostructure: TiN@TiO2 @In2 O3- x (OH)y are combined. This heterostructured material synergistically couples the metallic TiN and semiconducting In2 O3- x (OH)y phases via an interfacial semiconducting TiO2 layer, allowing it to drive the light-assisted reverse water gas shift reaction at a conversion rate greatly surpassing that of its individual components or any binary combinations thereof.

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.

A novel nanoparticulate polyacetylene-supported Pd(II) catalyst (NP-Pd(II)) for use in the aqueous Suzuki-Miyaura cross coupling reaction was successfully synthesized by simply treating an aqueous solution of PdCl42– with acetylene under ambient conditions. Electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy were employed to characterize the NP-Pd(II) structure in detail. These analyses demonstrated that the Pd atoms in the NP-Pd(II) were present as Pd(II) and were coordinated with both the Cl atoms and the C=C bonds of the polyacetylene. Both the homogeneous distribution of the Pd(II) along the polyacetylene backbone and the aggregation of the NP-Pd(II) in solution work in conjunction to make this material an ideal catalyst, combining the advantages of both homogeneous and heterogeneous catalysts.

In the search for new cathode materials for rechargeable lithium batteries, conversion-type materials have great potential because of their ability to achieve high specific capacities via the full utilization of transition metal oxidation states. Here, we report for the first time that copper phosphate can be used as a novel high-capacity cathode for rechargeable Li batteries, capable of delivering a reversible capacity of 360 mAh/g with two discharge plateaus of 2.7 and 2.1 V at 400 mA/g. The underlying reaction involves the formation as well as the oxidation of metallic Cu. The solid-state NMR, in situ XAFS, HR-TEM, and XRD results clearly indicate that Cu can react with Li3PO4 to form copper phosphate and LixCuyPO4 during the charging process, largely determining the reversibility of Cu3(PO4)2. This new reaction scheme provides a new venue to explore polyanion-type compounds as high-capacity cathode materials with conversion reaction processes.

We report in this article a detailed study on how to stabilize a first-row transition metal (M) in an intermetallic L1

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 H

The size dependence of the photothermal effect of palladium nanocrystals enables the selectivity of the solar powered heterogeneous catalytic hydrogenation of carbon dioxide to be finely tailored towards producing either carbon monoxide through the reverse water gas shift reaction, CO2 + H2 → CO + H2O, favored for small nanocrystals or to methane, via the Sabatier methanation reaction, CO2 + 4H2 → CH4 + 2H2O, preferred for larger nanocrystals. This is described by Geoffrey A. Ozin and co‐workers in article number 1700252.

This study has designed and implemented a library of hetero‐nanostructured catalysts, denoted as Pd@Nb2O5, comprised of size‐controlled Pd nanocrystals interfaced with Nb2O5 nanorods. This study also demonstrates that the catalytic activity and selectivity of CO2 reduction to CO and CH4 products can be systematically tailored by varying the size of the Pd nanocrystals supported on the Nb2O5 nanorods. Using large Pd nanocrystals, this study achieves CO and CH4 production rates as high as 0.75 and 0.11 mol h−1 gPd −1, respectively. By contrast, using small Pd nanocrystals, a CO production rate surpassing 18.8 mol h−1 gPd −1 is observed with 99.5% CO selectivity. These performance metrics establish a new milestone in the champion league of catalytic nanomaterials that can enable solar‐powered gas‐phase heterogeneous CO2 reduction. The remarkable control over the catalytic performance of Pd@Nb2O5 is demonstrated to stem from a combination of photothermal, electronic and size effects, which is rationally tunable through nanochemistry.

Most electrocatalysts for the ethanol oxidation reaction suffer from extremely limited operational durability and poor selectivity toward the CC bond cleavage. In spite of tremendous efforts over the past several decades, little progress has been made in this regard. This study reports the remarkable promoting effect of Ni(OH)

We synthesize a new type of hybrid Pd/WO

The electrochemical stability of platinum–iron oxide nanoparticles has been studied using X-ray absorption spectroscopy. Samples were monitored for changes in their surface structure and elemental composition after electrochemical cycling in acidic media, which were then correlated with their electronic properties and a thorough analysis of their electrocatalytic activities. In addition to the observation of significant surface restructuring, greater Fe content following electrochemical treatment was found to be associated with higher half-wave potentials and specific current densities (up to 0.965 ± 0.001 VRHE and 1.32 ± 0.03 × 10–5 mA cm–2, respectively). This work highlights the potential to improve the electrocatalytic activity of platinum–iron oxide nanoparticles by controlling the Fe content and platinum–iron bonding, and demonstrates the critical importance of characterizing these nanocatalysts both before and after use.

Bimetallic nanoparticles (NPs) consisting of small Pt clusters on the surface of larger metal NPs are potential catalysts that combine the advantages of reduced cost, high surface area, and a strong alloying interaction between Pt and the substrate. Herein we report the preparation of a series of small Pt clusters deposited on the surface of Ag NPs with systematically varied compositions (Ag93Pt7, Ag81Pt19, Ag72Pt28, and Ag65Pt35) via a galvanic replacement reaction. UV–vis spectroscopy, transmission electron microscopy, and inductively coupled plasma optical emission spectroscopy are used to provide evidence of NPs formation and evaluate their gross structural and compositional characteristics. Extended X-ray absorption fine structure (EXAFS) measurements at the Pt L3- and Ag K-edges are then used to elucidate the structural evolution of small surface Pt clusters as the Pt concentration is increased, allowing the formation mechanism of the bimetallic NPs to be deduced. X-ray absorption near-edge structur...