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Multifunctional complex molecules (CHM and BHM) were used to passivate interfacial defects, reduce the interfacial energy barrier, induce the orderly growth of perovskite crystals, and improve the PCE of HTL-free C-PSCs.

Two Ni12-multicubane topologies {Ni12W30} and {Ni12W27} have been synthesized. Magnetometry and homogeneous catalytic studies probing their properties as hydrogen evolution photocatalysts clearly distinguish {Ni12W30} and {Ni12W27} from Ni4 cubanes.

The high energy demand we currently face in society and the subsequent large consumption of fossil fuels cause its depletion and increase the pollution levels. The quest for the production of clean energy from renewable and sustainable sources remains open. The conversion of solar energy into hydrogen via the water-splitting process, assisted by photoresponsive semiconductor catalysts, is one of the most promising technologies. Significant progress has been made on water splitting in the past few years and a variety of photocatalysts active not only under ultra-violet (UV) light but especially with the visible part of the electromagnetic spectrum have been developed. Layered double hydroxides (LDH)-based materials have emerged as a promising class of nanomaterials for solar energy applications owing to their unique layered structure, compositional flexibility, tunable bandgaps, ease of synthesis and low manufacturing costs. This review covers the most recent research dedicated to LDH materials for photocatalytic water-splitting applications and encompasses a range of synthetic strategies and post-modifications used to enhance their performance. Moreover, we provide a thorough discussion of the experimental conditions crucial to obtaining improved photoactivity and highlight the impact of some specific parameters, namely, catalysts loading, cocatalysts, sacrificial agents, and irradiation sources. This review provides the necessary tools to select the election technique for adequately enhancing the photoactivity of LDH and modified LDH-based materials and concludes with a critical summary that outlines further research directions.

The design of active and selective co-catalysts constitutes one of the major challenges in developing heterogeneous photocatalysts for energy conversion applications. This work provides a comprehensive insight into thermally induced bottom-up generation and transformation of a series of promising Cu-based co-catalysts. We demonstrate that the volcano-type HER profile as a function of calcination temperature is independent of the type of the Cu precursor but is affected by changes in oxidation state and location of the copper species. Supported by DFT modeling, our data suggest that low temperature (200 °C) do not affect the Cu oxidation state, but induce a gradual, temperature-dependent surface-to-bulk diffusion of Cu, which results in interstitial, tetra-coordinated Cu+ species. The disappearance of Cu from the surface and the introduction of new defect states is associated with a drop in HER performance. This work examines electronic and structural effects that are in control of the photocatalytic activity and can be transferred to other systems for further advancing photocatalysis., Calcination of Cu/TiO2 is detrimental to its photocatalytic HER performance. We relate this to heat-activated Cu diffusion into the TiO2 lattice, which decreases accessibility of the Cu sites on the surface and generates charge recombination centers.

The ever‐growing interest in sustainable energy sources leads to a search for an efficient, stable, and inexpensive homogeneous water oxidation catalyst (WOC). Herein, the PO4 3− templated synthesis of three abundant‐metal‐based germanotungstate (GT) clusters Na15[Ge4PCo4(H2O)2W24O94] ⋅ 38H2O (Co4), Na2.5K17.5[Ge3PCo9(OH)5(H2O)4W30O115] ⋅ 45H2O (Co9), Na6K16[Ge4P4Co20(OH)14(H2O)18W36O150] ⋅ 61H2O (Co20) with non‐, quasi‐, or full cubane motifs structurally strongly reminiscent of the naturally occurring {Mn4Ca} oxygen evolving complex (OEC) in photosystem II was achieved. Under the conditions tested, all three GT‐scaffolds were active molecular WOCs, with Co9 and Co20 outperforming the well‐known Na10[Co4(H2O)2(PW9O34)2] {Co4P2W18} by a factor of 2 as shown by a direct comparison of their turnover numbers (TONs). With TONs up to 159.9 and a turnover frequency of 0.608 s−1 Co9 currently represents the fastest Co‐GT‐based WOC, and photoluminescence emission spectroscopy provided insights into its photocatalytic WOC mechanism. Cyclic voltammetry, dynamic light scattering, UV/Vis and IR spectroscopy showed recyclability and integrity of the catalysts under the applied conditions. The experimental results were supported by computational studies, which highlighted that the facilitated oxidation of Co9 was due to the higher energy of its highest occupied molecular orbital electrons as compared to Co4., Water oxidation: The stabilization of non‐, quasi‐ and full‐cubane topologies in three CoII germanotungstates (Co‐GT) [Ge4PCo4(H2O)2W24O94]15− (Co4), [Ge3PCo9(OH)5(H2O)4W30O115]20− (Co9), [Ge4P4Co20(OH)14(H2O)18W36O150]22− (Co20) via PO4 3− and GT lacunary ligands is reported. The Co‐GTs are active molecular water oxidation catalysts with Co9 and Co20 outperforming the non‐cubane [Co4(H2O)2(PW9O34)2]10− by a factor of 2, showing the structural and functional similarity of the GT‐encapsulated cubanes to the {Mn4Ca} oxygen evolving complex.

We report two Ni

A series of five decavanadates (V

Correction for ‘Interfacial engineering between SnO2/MAPbI3 by maleate pheniramine halides toward carbon counter electrode-based perovskite solar cells with 16.21% efficiency’ by Duoling Cao et al., Mater. Chem. Front., 2023, https://doi.org/10.1039/d2qm01149b.

Extraordinarily homogeneous, freestanding titania-loaded carbon spherogels can be obtained using Ti(acac)2(OiPr)2 in the polystyrene sphere templated resorcinol-formaldehyde gelation. Thereby, a distinct, crystalline titania layer is achieved inside every hollow sphere building unit. These hybrid carbon spherogels allow capitalizing on carbon's electrical conductivity and the lithium-ion intercalation capacity of titania.

Achieving efficient photocatalytic water splitting remains one of the most vital challenges in the photocatalysis field, as the performance of contemporary heterogeneous catalysts is still limited by their insufficient activity and low predictability. To address this challenge, this work takes inspiration from the concept of heterogeneous single-metal-site catalysts (HSMSCs) and follows the idea of site-isolation, aiming towards single-site co-catalyst species and a higher atom-utilization efficiency. We synthesized a set of photocatalysts through an adsorption-limited wet impregnation process using bare and phosphate-modified TiO2 as model supports and earth-abundant metals (Cu and Ni) with various loadings (0.008–5 wt.%) as co-catalyst species. The catalysts are characterized by TXRF for the determination of the real co-catalyst loadings, UV-vis and FTIR spectroscopes for semi-quantitative analysis of the metal state and binding modes to the substrate, and HRTEM for resolving the morphology of the sample’s surface. All samples were then evaluated towards the photocatalytic hydrogen evolution reaction (HER). We show that much higher turnover frequencies (TOFs) are obtained for both Cu- and Ni-based systems when lower co-catalyst loadings are used, which indicates an improved atom-utilization efficiency that reaches performances comparable to the noble Au co-catalyst. We also introduce a structural model to explain the observed TOF trends, which confirms that both earth-abundant systems undergo a strong structural reconstruction upon site-isolation towards smaller, perhaps even single-site-like species.

Here we report a systematic study of a series of non-noble-metal co-catalysts based on Co, Mn, Ni and Fe oxides that were prepared by wet impregnation of the corresponding acetylacetonate precursors onto a model TiO2 substrate, followed by their oxidative decomposition. We analyze thermal evolution of the impregnated M(acac)x–TiO2 composites with a combination of analytical methods and reveal strong differences in the precursor decomposition onsets and the resulting product composition, compared to the case of pure M(acac)x precursors. Consequent electron microscopy analyses of the resulting MOx–TiO2 composites indicate the presence of small (1–5 nm) amorphous MOx nanoparticles that are homogeneously distributed on the surface of the substrate TiO2. Complementing Raman and photoluminescence (PL) spectra confirm pronounced effects of MOx deposition on the state of TiO2 substrate and suggest strong electronic communication between the components. The composites obtained at 350 °C were further tested towards sacrificial hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) demonstrating the dynamic nature of the NiOx–TiO2 photocatalyst whose Ni0 active HER sites were generated in situ upon light exposure. In contrast, FeOx–TiO2, CoOx–TiO2, and NiOx–TiO2 were all active towards OER, featuring water oxidation ability in descending order, while XPS data of the samples after reaction indicate that partial oxidation of M species takes place during the course of the photocatalytic experiment. This work provides detailed insights on the wet chemistry-based preparation of MOx co-catalysts decorating oxide nanopowders including optimization of the thermal treatment, potential substrate effects and synergy as well as further prospects in photocatalysis.

Mesoporous photocatalysts have gained tremendous attention in the past decade by demonstrating that increased surface area and porosity can strongly improve their performance. In fact, all reports on mesoporous semiconductors corroborate this scenario. But is it possible to quantify and compare the reported advantages of the mesopores and the increased surface area between different works? In this contribution, we present a model that can evaluate the improvements in photocatalytic activity achieved by the introduction of mesoporosity independent of synthetic or test conditions. We exemplify this methodology focusing on photocatalytic hydrogen/oxygen evolution with sacrificial reagents, but also include examples of CO2 reduction and electrocatalysis. By correlating the relative increase in surface area to the relative increase in activity—in comparison to non-porous counterparts—we show that the origin of mesoporosity can have a pronounced influence on the activity enhancement and that different semicondu...

Nanostructuring constitutes a promising strategy to increase efficiency and stability of contemporary photocatalysts. Here, we report on the synthesis of highly crystalline Ta2O5 nanotubes (NTs) by using carbon nanotubes (CNTs) as sacrificial hard templates and elucidate the role of residual Fe nanoparticles—often used as catalyst for the CNT growth—on their photocatalytic performance toward H2 evolution. We show that, when using as grown CNTs, the resulting Ta2O5 NTs contained detectable amounts of Fe and possessed negligible photocatalytic activity. When CNTs were, however, purified from Fe by thermally annealing the CNTs at 2100 °C, the same synthetic procedure yielded pure Ta2O5 NTs that showed a 40-fold increase in activity compared to the Fe-containing counterpart. A complementary set of analytical techniques in a combination with additional model experiments indicate that the detrimental effect of the residual Fe on the photocatalytic activity originates from atomic doping and formation of a segreg...

We have prepared the first crystalline and 3D periodically ordered mesoporous quaternary semiconductor photocatalyst in an evaporation-induced self-assembly assisted soft-templating process. Using lab synthesized triblock-terpolymer poly(isoprene-b-styrene-b-ethylene oxide) (ISO) a highly ordered 3D interconnected alternating gyroid morphology was achieved exhibiting near and long-range order, as evidenced by small angle X-ray scattering (SAXS) and electron microscopy (TEM/SEM). Moreover, we reveal the formation process on the phase-pure construction of the material's pore-walls with its high crystallinity, which proceeds along a highly stable W5+ compound, by both in situ and ex situ analyses, including X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance (EPR). The resulting photocatalyst CsTaWO6 with its optimum balance between surface area and ordered mesoporosity ultimately shows superior hydrogen evolution rates over its non-ordered reference in photocatalytic hydrogen production. This work will help to advance new self-assembly preparation pathways towards multi-element multifunctional compounds for different applications, including improved battery and sensor electrode materials.

Molybdenum disulphide (MoS2) thin films have received increasing interest as device-active layers in low-dimensional electronics and also as novel catalysts in electrochemical processes such as the hydrogen evolution reaction (HER) in electrochemical water splitting. For both types of applications, industrially scalable fabrication methods with good control over the MoS2 film properties are crucial. Here, we investigate scalable physical vapour deposition (PVD) of MoS2 films by magnetron sputtering. MoS2 films with thicknesses from ≈10 to ≈1000 nm were deposited on SiO2/Si and reticulated vitreous carbon (RVC) substrates. Samples deposited at room temperature (RT) and at 400 °C were compared. The deposited MoS2 was characterized by macro- and microscopic X-ray, electron beam and light scattering, scanning and spectroscopic methods as well as electrical device characterization. We find that room-temperature-deposited MoS2 films are amorphous, of smooth surface morphology and easily degraded upon moderate laser-induced annealing in ambient conditions. In contrast, films deposited at 400 °C are nano-crystalline, show a nano-grained surface morphology and are comparatively stable against laser-induced degradation. Interestingly, results from electrical transport measurements indicate an unexpected metallic-like conduction character of the studied PVD MoS2 films, independent of deposition temperature. Possible reasons for these unusual electrical properties of our PVD MoS2 thin films are discussed. A potential application for such conductive nanostructured MoS2 films could be as catalytically active electrodes in (photo-)electrocatalysis and initial electrochemical measurements suggest directions for future work on our PVD MoS2 films.

Crystalline Ni/Au bimetallic oxide nanoparticles with various forms of crystallographic systems and defects were generated by femtosecond laser ablation of nickel–gold target in alcoholic solvents. The nature of the liquid can influence the chemical composition, stability, and size distribution of laser-synthesized nanoparticles. In ethanol, bimodal crystalline bimetallic Ni/Au oxide nanoparticles with median size of 15 nm were synthesized. The laser ablation of Ni/Au target in isopropanol and butanol led to nearly monomodal size distribution with median size of 10 and 13 nm, respectively. High-resolution transmission electron microscopy of Ni/Au oxide nanoparticles in butanol, revealed a graphitic shell of a few atomic layers. In this context, two suggested mechanisms were considered. First of all, the high photon intensity of femtosecond laser pulses can induce direct photolysis of liquid media. Secondly, the formation of supercritical temperature solvent due to the interaction of solvent with molten metal layer at liquid–metal interface can trigger pyrolysis of solvent. These mechanisms can contribute to butanol decomposition and encapsulation of Ni/Au oxide bimetallic nanoparticles with graphite shell. Graphite shell can create a better colloidal stability by preventing nanoparticles from further growth and agglomeration.

We synthesized a series of isostructural MIL-125-Ti with various terephthalic: amino-terephthalic acid ratios and evaluated their photostability and performance for photocatalytic hydrogen evolution in aqueous solutions with different hole scavengers. We demonstrate that the commonly used triethanolamine corroded the MOFs under photocatalytic conditions, in contrast to methanol. The combination of MIL-125-Ti and methanol outperformed the photocatalytic activity of NH2-MIL-125-Ti by 45 times under broad UV irradiation. Photoluminescence spectroscopy under simulated photocatalytic conditions and in solid-state as well as time-resolved emission studies reveal that the holes residing in the metal-oxo cluster can be effectively scavenged by methanol, leading to high HER activity, while the holes residing in the NH2-groups in the ligand favour charge recombination and are thus detrimental to the photocatalytic performance. The mixed-ligand MOFs follow a dual-excitation pathway, introducing new states and transitions. These results are expected to advance our understanding of MOF-based photocatalysis.

Hierarchical hollow microspheres (HHMSs) constitute a very popular class of materials for use as drug-delivery carriers, photocatalysts and electrode materials in batteries, owing to their large, porous surface area and mechanical integrity during intercalation reactions. Here, we used a template- and additive-free hydrothermal route to prepare an unusually shaped SnO2 material that comprises a hollow spherical morphology with uniform diameters and very thin petal-like nano-sheets grown perpendicularly on the sphere's surface, resembling a “chestnut cupule”. We thoroughly investigated the formation mechanism by 119Sn Mossbauer spectroscopy, powder X-ray diffraction and X-ray photoelectron spectroscopy. Key to this process is the ultrasonic pre-treatment of an aqueous SnCl2 solution, followed by Ostwald “inside-out” ripening upon hydrothermal processing. This unique morphology has greatly improved the storage capacity and cycling performance of SnO2 as an anode material for lithium and sodium ion batteries compared with conventional SnO2 materials.

Correction for ‘Elucidating the formation and active state of Cu co-catalysts for photocatalytic hydrogen evolution’ by Jasmin S. Schubert et al., J. Mater. Chem. A, 2021, DOI: 10.1039/d1ta05561e.

In this work we synthesized well-ordered, Ta2O5 films with a 3D-interconnected gyroid mesopore architecture with large pore sizes beyond 30 nm and extended crystalline domains through self-assembly of tailor-made triblock-terpolymers. This has effectively eliminated diffusion limitations inherent to previously reported mesoporous photocatalysts and resulted in superior hydrogen evolution with apparent quantum yields of up to 4.6% in the absence of any cocatalyst. We further show that the injection barrier at the solid–liquid interface constitutes a key criterion for photocatalytic performance and can be modified by the choice of the carbon template. This work highlights pore and surface engineering as a promising tool towards high-performance mesoporous catalysts and electrodes for various energy-related applications.

We demonstrate a unique route towards hierarchical assemblies of mesoporous TiO2 and CNT/TiO2 photocatalysts by a combination of electrospinning and sol–gel methods. The resulting materials exhibit a mesoporous network of highly crystalline, well-connected inorganic nanocrystals with an order of magnitude higher photocatalytic activity than individualised TiO2 nanoparticles. The in-situ combination of small amounts of MWCNTs with TiO2 to form an electrospun CNT/TiO2 hybrid further enhanced the oxide photoactivity considerably, reaching hydrogen evolution rates of 1218 μmol/h in water splitting in the presence of sacrificial reagents under UV irradiation. We also discuss the effect of oxygen vacancies on the oxide crystallisation and phase transformation. These vacancies lead to inter-bandgap states and a lower flat band potential that facilitates the photocatalytic process.

The effect of the conditions of polyacrylonitrile synthesis (nature of the solvent, homogeneity of the reaction medium, and type of initiation) on the conditions of formation of the polyconjugation system during the pyrolysis of polyacrylonitrile is studied. The controlled synthesis of polyacrylonitrile via radiation polymerization mediated by dibenzyl trithiocarbonate as a reversible addition-fragmentation chain-transfer agent at 25 and 80°C is performed for the first time. It is shown that the type of initiation in reversible addition-fragmentation chain-transfer polymerization (material initiation or radiolysis) strongly affects the structure of the formed polyconjugation system.

The polymerization of acrylonitrile mediated by various trithiocarbonates as reversible addition-fragmentation chain-transfer agents is studied. It is shown that, when polymerization is performed in DMSO, a narrowly dispersed PAN with a controlled molecular mass can be prepared. The pseudoliving radical polymerization of acrylonitrile is conducted for the first time via the reversible addition-fragmentation chaintransfer mechanism in carbon dioxide at an increased pressure. The structure of the polymers is investigated via NMR and IR spectroscopy. As shown by DSC and IR pyrolysis, the thermal behavior of PAN is determined by its molecular mass, the width of the molecular-mass distribution, and the conditions of synthesis. The incorporation of functional groups of the reversible addition-fragmentation chain-transfer agent into a macromolecule changes the structure of the polyconjugated system and makes it possible to control the conditions of its formation.

The hybridisation of metal oxides and nanocarbons has created a promising new class of functional materials for environmental and sustainable energy applications. The performance of such hybrids can be further improved by rationally designing interfaces and morphologies. Atomic layer deposition (ALD) is among the most powerful techniques for the controlled deposition of inorganic compounds, due to its ability to form conformal coatings on porous substrates at low temperatures with high surface sensitivity and atomic control of film thickness. The hydrophobic nature of the nanocarbon surface has so far limited the applicability of ALD on CNTs. Herein we investigate the role of structural defects in CNTs, both intrinsic and induced by acid treatment, on coverage, uniformity and crystallinity of ZnO coatings. Furthermore, we demonstrate the potential of small aromatic molecules, including benzyl alcohol (BA), naphthalene carboxylic acid (NA) and pyrene carboxylic acid (PCA), as active nucleation sites and linking agents. Importantly, only PCA exhibits sufficiently strong interactions with the pristine CNT surface to withstand desorption under reaction conditions. Thus, PCA enables a versatile and non-destructive alternative route for the deposition of highly uniform metal oxide coatings onto pristine CNTs via ALD over a wide temperature range and without the typical surface corrosion induced by covalent functionalisation. Importantly, preliminary tests demonstrated that the improved morphology obtained with PCA has indeed considerably increased the hybrid's photocatalytic activity towards hydrogen evolution via sacrificial water splitting. The concept demonstrated in this work is transferable to a wide range of other inorganic compounds including metal oxides, metal (oxy)nitrides and metal chalcogenides on a variety of nanocarbons. Refereed/Peer-reviewed

Hybridizing inorganic nanomaterials with carbon nanotubes and graphene constitutes a powerful approach towards creating new functional materials for environmental and sustainable energy applications. Their superior performance originates from synergistic effects based on charge and energy transfer processes at the hybrid's interfaces. However, only few studies have been devoted so far towards rationally designing these hybrids. In this work we demonstrate that engineering interfaces as well as the morphology of the functional inorganic compound can maximise the synergistic effects in hybrids, thus further enhancing the hybrid's photocatalytic properties. Particularly, we have stimulated the growth of ultra-thin single-crystalline layers of tantalum (v) oxide (Ta2O5) with preferred orientation at substantially reduced crystallisation temperatures, by utilising the graphitic CNT surfaces as seed crystals through heterogeneous nucleation. The resulting hybrids possess outstanding activities for the evolution of hydrogen via sacrificial water splitting that are about 35 times higher than those of comparable materials such as tantalates. The additional improvements in this hybrid are attributed to the single-crystalline nature of the coating, which alleviates transport of electrons to the interface, as well as the formation of a Schottky-type junction between the metallic nanocarbon and the semiconducting metal oxide, which facilitates charge transfer and thus charge separation at the interface. © The Royal Society of Chemistry. Refereed/Peer-reviewed

Hybridizing nanocarbons, such as carbon nanotubes (CNTs) or graphene, with an active material is a powerful strategy towards designing next-generation functional materials for environmental and sustainable energy applications. While research on nanocomposites, created by dispersing the nanocarbon into polymer or ceramic matrices, began almost immediately after the popularization of CNTs and graphene in 1991 and 2004, respectively, nanocarbon hybrids are a relatively recent addition to the family of composite materials. In contrast to nanocomposites, which typically combine the intrinsic properties of both compounds, nanocarbon hybrids additionally provide access to both a large surface area required for gas/liquid-solid interactions and an extended interface, through which charge and energy transfer processes create synergistic effects that result in unique properties and superior performance. This progress report looks at the history of research on nanocarbons (fullerenes, CNTs and graphene) and their composites and hybrids, presents the origin of synergistic effects, reviews the most intriguing results on nanocarbon hybrid performance in heterogeneous catalysis, electrocatalysis, photocatalysis, batteries, supercapacitors, photovoltaics and sensors, and discusses remaining challenges and future research directions. Nanocarbon hybrids are a class of material in which a nanocarbon (e.g., carbon nanotube, graphene) is in close contact with a second active component. Hybrids prepared by a range of synthesis strategies excel in a variety of energy and environmental applications such as catalysis, energy storage, energy conversion and sensors. usc Refereed/Peer-reviewed

Hybridizing nanocarbons, such as carbon nanotubes (CNTs) or graphene (G), with inorganic and organic compounds is a powerful strategy to designing next-generation functional materials for environmental and sustainable energy applications. While research on nanocomposites, created by dispersing the nancarbon into polymer and ceramic matrices, was started almost immediately after the popularization of CNTs and graphene in 1991 and 2004, respectively, nanocarbon hybrids are a relatively recent addition to the family of composite materials. In contrast to nanocomposites, which typically combine the intrinsic properties of both compounds, nanocarbon hybrids additionally provide access to both a large surface area required for gas-liquid-solid interactions and an extended interface, through which charge and energy transfer processes create synergistic effects that result in unique properties and superior performance. This chapter summarizes the current progress of nanocarbon hybrid materials and reviews the most intriguing results on their performance in heterogenous catalysis, electrocatalysis, photocatalysis, batteries, supercapacitors, photovoltaics and sensors. Refereed/Peer-reviewed