Correction: High photocatalytic yield in the non-oxidative coupling of methane using a Pd-TiO nanomembrane gas flow-through reactor.

[This corrects the article DOI: 10.1039/D4EY00112E.].

High photocatalytic yield in the non-oxidative coupling of methane using a Pd-TiO nanomembrane gas flow-through reactor.

The photocatalytic non-oxidative coupling of methane (NOCM) is a highly challenging and sustainable reaction to produce H and C hydrocarbons under ambient conditions using sunlight. However, there is a lack of knowledge, particularly on how to achieve high photocatalytic yield in continuous-flow reactors. To address this, we have developed a novel flow-through photocatalytic reactor for NOCM as an alternative to the conventionally used batch reactors.

X-ray Characterizations of Exfoliated MoS Produced by Microwave-Assisted Liquid-Phase Exfoliation.

An X-ray analysis of exfoliated MoS, produced by means of microwave-assisted liquid-phase exfoliation (LPE) from bulk powder in 1-methyl-2-pyrrolidone (NMP) or acetonitrile (ACN) + 1-methyl-2-pyrrolidone (NMP) solvents, has revealed distinct structural differences between the bulk powder and the microwave-exfoliated samples. Specifically, we performed X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements to identify the elements of our exfoliated sample deposited on a Si substrate by drop-casting, as well as their chemical state and its structural crystalline phase. In the exfoliated sample, the peaks pattern only partially resemble the theoretical Miller indices for MoS.

Water Structure in the First Layers on TiO: A Key Factor for Boosting Solar-Driven Water-Splitting Performances.

The water hydrogen-bonded network is strongly perturbed in the first layers in contact with the semiconductor surface. Even though this aspect influences the outer-sphere electron transfer, it was not recognized that it is a crucial factor impacting the solar-driven water-splitting performances. To fill this gap, we have selected two TiO anatase samples (with and without B-doping), and by extensive experimental and computational investigations, we have demonstrated that the remarkable 5-fold increase in water-splitting photoactivity of the B-doped sample cannot be ascribed to effects typically associated to enhanced photocatalytic properties, such as band gap, heterojunctions, crystal facets, and other aspects.

Catalysis for Carbon-Circularity: Emerging Concepts and Role of Inorganic Chemistry.

Carbon circularity is crucial for achieving a circular economy but has wider implications and impacts with respect to the circularity of materials. It has an in-depth transformative effect on the economy. CO recycling is a critical component for this objective, with catalysis and inorganic chemistry playing a determining role in achieving this challenge.

Interfacial Chemistry in the Electrocatalytic Hydrogenation of CO over C-Supported Cu-Based Systems.

Operando soft and hard X-ray spectroscopic techniques were used in combination with plane-wave density functional theory (DFT) simulations to rationalize the enhanced activities of Zn-containing Cu nanostructured electrocatalysts in the electrocatalytic CO hydrogenation reaction. We show that at a potential for CO hydrogenation, Zn is alloyed with Cu in the bulk of the nanoparticles with no metallic Zn segregated; at the interface, low reducible Cu(I)-O species are consumed. Additional spectroscopic features are observed, which are identified as various surface Cu(I) ligated species; these respond to the potential, revealing characteristic interfacial dynamics.

Understanding the complexity in bridging thermal and electrocatalytic methanation of CO.

The selective methanation of CO is an important research area to meet the net-zero emission targets. Furthermore, it is crucial to develop solutions to achieve carbon neutrality, hydrogen utilization, carbon circularity, and chemical-energy storage. This conversion can be realized the thermocatalytic multistep power-to-X route or by direct electro- (or photoelectro)-catalytic technologies.

The Role of Substrate Surface Geometry in the Photo-Electrochemical Behaviour of Supported TiO Nanotube Arrays: A Study Using Electrochemical Impedance Spectroscopy (EIS).

Highly ordered TiO nanotube (NT) arrays grown on Ti mesh and Ti foil were successfully prepared by a controlled anodic oxidation process and tested for water photo-electrolysis. Electrochemical impedance spectroscopy (EIS), combined with other electrochemical techniques (cyclic voltammetry and chronoamperometry) in tests performed in the dark and under illumination conditions, was used to correlate the photoactivity to the specific charge transfer resistances associated with a 3D (mesh) or 2D (foil) geometry of the support. The peculiar structure of the nanotubes in the mesh (with better light absorption and faster electron transport along the nanotubes) strongly impacts the catalytic performances under illumination.

Advanced (photo)electrocatalytic approaches to substitute the use of fossil fuels in chemical production.

Electrification of the chemical industry for carbon-neutral production requires innovative (photo)electrocatalysis. This study highlights the contribution and discusses recent research projects in this area, which are relevant case examples to explore new directions but characterised by a little background research effort. It is organised into two main sections, where selected examples of innovative directions for electrocatalysis and photoelectrocatalysis are presented.

Catalysis for -Chemistry: Need and Gaps for a Future De-Fossilized Chemical Production, with Focus on the Role of Complex (Direct) Syntheses by Electrocatalysis.

The prospects, needs and limits in current approaches in catalysis to accelerate the transition to -chemistry, where this term indicates a fossil fuel-free chemical production, are discussed. It is suggested that -chemistry is a necessary element of the transformation to meet the targets of net zero emissions by year 2050 and that this conversion from the current petrochemistry is feasible. However, the acceleration of the development of catalytic technologies based on the use of renewable energy sources (indicated as reactive catalysis) is necessary, evidencing that these are part of a system of changes and thus should be assessed from this perspective.

Assessment of hydrogen production from municipal solid wastes as competitive route to produce low-carbon H.

An economic and CO emission impact assessment of the production of H from municipal solid waste in the two configurations of retrofitting an existing waste to energy plant with an electrolysis unit (WtE + El) and of hydrogen production via waste gasification (WtH) is made with respect to reference cases of H production by steam reforming of methane (SMR) or of water electrolysis (El). The results are analyzed with reference to two scenarios depending on whether the fate of waste disposal emissions for SMR and El is accounted. The costs of H production as a function of waste gate fee and CO taxation as well as the CO emissions for both scenarios and the four cases of H production analyzed are reported.

Reuse of CO in energy intensive process industries.

Closing the carbon cycle and enabling a carbon circular economy in energy intensive industries (iron and steel, cement, refineries, petrochemistry and fertilizers) are topics of increasing interest to meet the demanding target of defossilizing the production. The focus of this perspective contribution is on CO reuse technologies in this context. While this is a topic with abundant literature, the analysis of applying CO reuse technologies evidences the need to go beyond those receiving most of the attention today, such as conversion of CO to methanol.

Tuning the Chemical Properties of Co-Ti C T MXene Materials for Catalytic CO Reduction.

MXenes, a novel family of 2D materials, are energy materials that have gained considerable attention, particularly for their catalytic applications in emerging areas such as CO and N hydrogenation. Herein, for the first time, it is shown that the surface reducibility of Ti C T MXene can be tuned by N doping, which induces a change in the catalytic properties of supported Co nanoparticles. Pristine Co-Ti C T MXene favors CO production during CO hydrogenation, whereas CH production is favored when the MXene is subjected to simple N doping.

Nanocarbon for Energy Material Applications: N Reduction Reaction.

Nanocarbons are an important class of energy materials and one relevant application is for the nitrogen reduction reaction, i.e., the direct synthesis of NH from N and H O via photo- and electrocatalytic approaches.

Peptide Gelators to Template Inorganic Nanoparticle Formation.

The use of peptides to template inorganic nanoparticle formation has attracted great interest as a green route to advance structures with innovative physicochemical properties for a variety of applications that range from biomedicine and sensing, to catalysis. In particular, short-peptide gelators offer the advantage of providing dynamic supramolecular environments for the templating effect on the formation of inorganic nanoparticles directly in the resulting gels, and ideally without using further reductants or chemical reagents. This mini-review describes the recent progress in the field to outline future research directions towards dynamic functional materials that exploit the synergy between supramolecular chemistry, nanoscience, and the interface between organic and inorganic components for advanced performance.

Comparing Molecular Mechanisms in Solar NH Production and Relations with CO Reduction.

Molecular mechanisms for N fixation (solar NH) and CO conversion to C2+ products in enzymatic conversion (), electrocatalysis, metal complexes and plasma catalysis are analyzed and compared. It is evidenced that differently from what is present in thermal and plasma catalysis, the electrocatalytic path requires not only the direct coordination and hydrogenation of undissociated N molecules, but it is necessary to realize features present in the mechanism. There is the need for (i) a multi-electron and -proton simultaneous transfer, not as sequential steps, (ii) forming bridging metal hydride species, (iii) generating intermediates stabilized by bridging multiple metal atoms and (iv) the capability of the same sites to be effective both in N fixation and in CO reduction to C2+ products.

Enhancing N Fixation Activity by Converting Ti C MXenes Nanosheets to Nanoribbons.

Metal carbides M C (MXenes) with two-dimensional (2D) structure have been indicated as promising materials for N fixation, with the activity being related to edge planes. Here, it is instead demonstrated that the transformation from a 2D- (nanosheets) to a 3D-type nanostructure (nanoribbons) leads to a significant enhancement of the N fixation activity due to the formation of exposed Ti-OH sites. A linear relationship is observed between ammonia formation rate and amount of oxygen on the surface of Ti C MXene.

Elucidating the mechanism of the CO methanation reaction over Ni-Fe hydrotalcite-derived catalysts via surface-sensitive in situ XPS and NEXAFS.

Hydrotalcite-derived Ni and Fe-promoted hydrotalcite-derived Ni catalysts were found to outperform industrial catalysts in the CO methanation reaction, however the origin of the improved activity and selectivity of these catalysts is not clear. Here, we report a study of these systems by means of in situ X-ray photoelectron spectroscopy and near-edge X-ray absorption spectroscopy elucidating the chemical nature of the catalysts surface under reaction conditions and revealing the mechanism by which Fe promotes activity and selectivity towards methane. We show that the increase of the conversion leads to hydroxylation of the Ni surface following the formation of water during the reaction.

Highly Efficient Metal-Free Nitrogen-Doped Nanocarbons with Unexpected Active Sites for Aerobic Catalytic Reactions.

Nitrogen (N)-doped nanocarbons (NDN) as metal-free catalysts have elicited considerable attention toward selective oxidation of alcohols with easily oxidizable groups to aldehydes in the past few years. However, finding a new NDN catalytic material that can meet the requirement of the feasibility on the aerobic catalytics for other complicated alcohols is a big challenge. The real active sites and the corresponding mechanisms on NDN are still unambiguous because of inevitable coexistence of diverse edge sites and N species based on recently reported doping methods.

CO Reduction of Hybrid Cu O-Cu/Gas Diffusion Layer Electrodes and their Integration in a Cu-based Photoelectrocatalytic Cell.

Cu O/gas diffusion layer (GDL) electrodes prepared by electrodeposition were studied for the electrocatalytic reduction of CO . The designed electrode was also tested in solar-light-induced CO conversion in combination with a CuO/NtTiO photoanode using a compact photoelectrocatalytic (PEC) cell. Both PEC cell electrodes were prepared using non-critical raw materials and low cost, easily scalable procedures.

Catalysis by hybrid sp/sp nanodiamonds and their role in the design of advanced nanocarbon materials.

Hybrid sp2/sp3 nanocarbons, in particular sp3-hybridized ultra-dispersed nanodiamonds and derivative materials, such as the sp3/sp2-hybridized bucky nanodiamonds and sp2-hybridized onion-like carbons, represent a rather interesting class of catalysts still under consideration. Their characteristics, properties and catalytic reactivity are presented, with an analysis of the state-of-the-art of their use in gas- and liquid-phase reactions, including photo- and electro-catalysis. It is remarked that intrinsic differences exist between these and other nanostructured carbon catalysts.

2D Oxide Nanomaterials to Address the Energy Transition and Catalysis.

2D oxide nanomaterials constitute a broad range of materials, with a wide array of current and potential applications, particularly in the fields of energy storage and catalysis for sustainable energy production. Despite the many similarities in structure, composition, and synthetic methods and uses, the current literature on layered oxides is diverse and disconnected. A number of reviews can be found in the literature, but they are mostly focused on one of the particular subclasses of 2D oxides.

Waste to Chemicals for a Circular Economy.

The implementation of a circular economy is a fundamental step to create a greater and more sustainable future for a better use of resources and energy. Wastes and in particular municipal solid waste represent an untapped source of carbon (and hydrogen) to produce a large range of chemicals from methane to alcohols (as methanol or ethanol) or urea. The waste to chemical process and related economics are assessed in this concept article to show the validity of such solution both from an economic point of view and from an environmental perspective considering the sensible reduction in greenhouse gas emissions with respect to conventional production from fossil fuels.

Operando spectroscopy study of the carbon dioxide electro-reduction by iron species on nitrogen-doped carbon.

The carbon-carbon coupling via electrochemical reduction of carbon dioxide represents the biggest challenge for using this route as platform for chemicals synthesis. Here we show that nanostructured iron (III) oxyhydroxide on nitrogen-doped carbon enables high Faraday efficiency (97.4%) and selectivity to acetic acid (61%) at very-low potential (-0.