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Inspired by simulation analysis, we found that Cu decoration could enhance the NH3 production rate of InVO4 through promoting N2 adsorption and reducing the activation energy of the key hydrogenation step. 5% Cu/InVO4 exhibited an optimal NH3 yield of 195.11 μmol gcat−1 h−1, approximately six times higher than that of InVO4. Cu/InVO4 was also fabricated by upcycling Cu from electroplating sludge, achieving a gratifying nitrogen fixation performance of 154.13 μmol gcat−1 h−1. [ABSTRACT FROM AUTHOR]

Over the past few decades, photocatalytic CO2 reduction has remained a prominent and growing research field due to the efficient conversion of CO2 to value-added chemicals. Among the various photocatalytic performances, product selectivity has garnered considerable attention, which is the focus of this review. Herein, we first introduce the general background of photocatalytic CO2 reduction, then according to the sequence of the entire reaction process, the adsorption and activation of reactants, the formation and stabilization of intermediates, and the desorption of products are summarized. After introducing each of the above steps that could mediate the final products, several modification techniques to improve the product selectivity are highlighted, including noble metal decoration, metal and non-metal doping, vacancy engineering, facet engineering, composite construction, and hydroxyl modification. Finally, current challenges and opportunities of interest in this rich field are discussed. [ABSTRACT FROM AUTHOR]

Semiconductor vacancy engineering has remained a prominent growing field over the past several decades. Modulating electronic structures and surface properties has sparked considerable interest in vacancy-modified photocatalysts. Given vacancy-mediated photocatalysis has only been developed for a relatively short period, significant advance has been made in enhancing light absorption over the full solar spectrum, the efficiency of charge transfer and separation and surface reaction kinetics. This review seeks to highlight the recent impressive progress in vacancy-enhanced photocatalysis. First, we summarize the crafting and characterization of vacancies after defining the classification of vacancies. Second, current developments of semiconductor vacancy engineering in several photocatalysts (i.e., metal oxides, hydroxides, sulfides, Sillén phase related bismuth-containing materials and g-C3N4) are emphasized, focusing on the mechanism of vacancies in regulating the photocatalytic performance. Finally, prospects and challenges regarding vacancy engineering of photocatalytic materials are concluded. [ABSTRACT FROM AUTHOR]

The past few decades have witnessed rapid advances in two dimensional (2D) materials as they carry a stellar set of unique properties over their bulk counterparts. Two families of 2D materials, namely, layered 2D materials and nonlayered 2D materials, have garnered considerable attention. Layered 2D materials have been widely used in electronic devices, catalysis, and bioelectronics due to their tunable energy band structure, and superlative physical and chemical properties. By contrast, dangling bonds on the surface of non-layered 2D materials and intrinsic crystal distortion endow them with abundant active sites for use in energy storage and photodetectors. In this context, the ability to effectively exfoliate 2D materials is the key to these applications. This review highlights the recent developments pertaining to exfoliation techniques applicable to 2D layered and non-layered materials and the corresponding exfoliation mechanisms. In particular, some emerging exfoliation techniques are emphasized. Subsequently, how these exfoliation techniques facilitate the application of 2D materials in electronic devices, catalysis, batteries, and supercapacitors is summarized. Finally, an outlook is provided with an aim to lay out the promising future research directions on 2D materials produced by exfoliation approaches. [ABSTRACT FROM AUTHOR]

Cost-effective, highly efficient, and durable catalyst electrodes play a critical role in large-scale water splitting. Although bimetallic phosphides show great potential in electrocatalytic water splitting, the synergistic effect between different active sites has not been investigated to date in detail, which implies lack of an effective strategy to optimize the water splitting performance in a reasonable way. Here we realize robust oxygen evolution (OER) performance with an extremely low overpotential (500 mA cm−2@255 mV), low Tafel slope (29.1 mV dec−1), and superior stability by controlling the Fe sites on the Ni–Fe–P surface. The prepared OER electrode employs non-noble metal catalysts for superior oxygen evolution performance and meets the requirements of commercial water electrolyzers. In addition, remarkable hydrogen evolution (HER) performance with prominent stability is also achieved by reducing the content of Fe dopant. Our theoretical calculations reveal that improved chemisorption of O-containing intermediates induced by Fe doping contributes to the enhanced OER performance and water molecule chemisorption, which is sensitive to the Fe content, is the primary cause affecting alkaline HER performance. This work highlights controllable water splitting performance on the Ni–Fe–P surface by precisely manipulating the surface active Fe-sites. [ABSTRACT FROM AUTHOR]

The performance of organic–inorganic perovskite-based devices has rapidly increased in recent years, but the poor air-stability of perovskite materials limits their widespread applications. Here we report a strategy to enhance the air-stability of the CH3NH3PbI3 (MAPbI3) perovskite with trilayer graphene on top of it by an anhydrous transfer method. Our morphological characterization shows good adhesion at the interface of the graphene/perovskite film. The time dependent X-ray diffraction spectra of perovskite films demonstrate enhanced stability of graphene-coated films during exposure to the ambient environment. The protected perovskite film is also evidenced by photoluminescence and absorbance measurements. This graphene transfer method without the use of water has the potential to enhance the air-stability of perovskites as well as other moisture sensitive materials. [ABSTRACT FROM AUTHOR]

Robust hydrogen evolution reaction (HER) in alkaline solution using a cost-effective catalyst is still a critical challenge for industrial H2O electrolysis. The dramatic depletion of interfacial H2O and hindered OH− diffusion bring about a harsh interfacial environment and thereby lead to sluggish hydrogen evolution. Here we develop heterogeneous catalysts based on defect-rich three-dimensional graphene (M/3D graphene) and achieve improved HER kinetics via surface hydroxyl group modification on the graphene surface. Our theoretical studies suggest that the surface hydroxyl groups derived from the hydroxylation process effectively attract multi-overlayer H2O clusters without any thermodynamic barrier and form a reservoir to continuously supply H2O for catalytic sites. Electrochemical characterizations indicate that the HER kinetics per active electrochemical surface area have been greatly improved after crafting abundant hydroxyl groups on the 3D graphene framework, which can be attributed to sufficient proton donors and an ameliorative interfacial pH environment. Benefiting from the surface hydroxyl group modification, the MoS2/3D graphene structure facilitates the HER at a low onset potential of 60 mV in alkaline medium and exhibits excellent durability after 3000 cycles. This surface modification strategy reveals the importance of interfacial H2O supply in HER kinetics and provides general guidance on designing highly efficient catalysts in alkaline medium. [ABSTRACT FROM AUTHOR]

The ability to synthetically tune the size, shape, composition and architecture of inorganic nanostructures offers enormous opportunities to explore the fundamental structure–property relationships that occur uniquely at the nanoscale, and engineer greater functionality and design complexity into new material systems. Core/shell nanoparticles represent an important class of nanostructured materials that have garnered considerable interest. The success in producing core/shell nanoparticles with strictly controlled core diameter and shell thickness and tailoring their material properties relies crucially on the epitaxial growth of the shell material over the highly curved surface of the spherical core. However, effective methods to yield such high-quality core/shell nanoparticles are comparatively few and limited in scope. Here, we develop a robust nonepitaxial growth strategy to create uniform plasmonic/semiconducting core/shell nanoparticles with precisely controlled dimensions by capitalizing on amphiphilic star-like triblock copolymers as nanoreactors. The diameter of the plasmonic core and the thickness of the semiconductor shell can be independently and precisely regulated by tailoring the molecular weights (i.e., the lengths) of the inner and intermediate blocks of star-like triblock copolymers, respectively. The successful crafting of plasmonic/semiconducting core/shell nanoparticles was corroborated by the composition and structural characterizations. These functional nanoparticles exhibited largely improved photocatalytic activities, which can be attributed to the localized surface plasmon-mediated light harvesting enhancement of the plasmonic core and the built-in internal electric field. This nonepitaxial growth strategy offers new levels of tailorability in the dimensions, compositions and architectures of nanomaterials with engineered functionalities for applications in catalytic, electronic, optic, optoelectronic and sensory materials and devices. [ABSTRACT FROM AUTHOR]

By subjecting amorphous titanium dioxide (TiO2) colloidal spheres as a scaffold to a two-step external template-free hydrothermal treatment, anatase TiO2 hollow spheres with an average diameter of 410 nm and shell thickness of 65 nm were successfully yielded. Such hollow TiO2 nanostructures possessed a large surface area, abundant active sites and reduced Li ion diffusion path and thus were highly favorable for use in TiO2-based lithium ion batteries (LIB). Electrochemical measurements revealed that as-prepared TiO2 hollow spheres exhibited specific discharge capacities of 296, 185, 118, 66 and 37 mA h g−1 at 0.1 C, 1 C, 2 C, 5 C and 10 C, respectively. This is in sharp contrast to the considerably lower values obtained in TiO2 solid nanoparticles (i.e., 182, 119, 81, 43 18 mA h g−1 at discharge rates of 0.1 C, 1 C, 2 C, 5 C and 1 0 C, respectively). Interestingly, TiO2 hollow spheres showed a large irreversible capacity loss and relatively low cycling performance due to the residual chemisorbed water in TiO2 and hydroxyl groups present on the TiO2 surface. A solid electrolyte interface (SEI) layer composed primarily of Li2CO3, lithium alkyl carbonates and organic phosphates was thus formed on the surface of hollow TiO2 spheres, thereby leading to an increased internal cell impedance and the decreased rate and cycling performance. The subsequent high-temperature annealing effectively removed chemisorbed water and hydroxyls on the TiO2 surface. As a consequence, annealed TiO2 hollow spheres rendered markedly improved rate stability and cycle performance in the resulting TiO2-based LIBs. The specific discharge capacities at rates of 5 C and 10 C were 77 mA h g−1 and 50 mA h g−1, which are considerably larger than those obtained from as-prepared TiO2 hollow spheres. Moreover, compared to only 42.1% for as-prepared hollow TiO2 spheres, a capacity retention as high as 93.5% over 200 cycles at 1 C was achieved for annealed hollow TiO2 spheres. [ABSTRACT FROM AUTHOR]

An ultrasound-assisted deposition technique was adopted to construct NiO nanoparticles on TiO[sub 2] nanotube arrays (NiO-TiO[sub 2] NTAs) which were prepared by three-step electrochemical anodization in an ethylene glycol system. The NiO nanoparticles were found to deposit on the surface of the highly oriented TiO[sub 2] nanotubes. NiO-TiO[sub 2] NTAs exhibited improved photochemical capability under UV irradiation. Compared with TiO[sub 2] NTAs, a more than 2.56-fold enhancement in photocurrent response was achieved using the NiO-TiO[sub 2] NTAs. The maximum incident photon to charge carrier generation efficiency (IPCE) values of NiO-TiO[sub 2] NTAs and TiO[sub 2] NTAs were 83.5% and 22.2%, respectively. The photocatalytic activities of NiO-TiO[sub 2] NTAs were evaluated by the photodegradation of methylene blue (MB) aqueous solution. The kinetic constant of photocatalytic degradation of MB using NiO-TiO[sub 2] NTAs prepared by ultrasonic deposition for 1.0 h was 1.9 times higher than that using TiO[sub 2] NTAs. The enhanced photocurrent response and photocatalytic activity with NiO-TiO[sub 2] NTAs were attributed to the formation of the NiO-TiO[sub 2] p-n junctions. [ABSTRACT FROM AUTHOR]

ZnFe2O4 coupled TiO2 nanotube arrays (ZnFe2O4–TiO2 NTAs) were synthesized by modifying TiO2 nanotube arrays with ZnFe2O4 nanoparticles. Self-organized TiO2 NTAs with a tube diameter of 100 nm and length of 400 nm were prepared by an electrochemical anodization method. ZnFe2O4 nanoparticles were deposited on the surface of TiO2 nanotubes through a facile hydrothermal route. The modification of ZnFe2O4 nanoparticles extended the photoresponse of TiO2 nanotube arrays into the visible light region. Under visible light irradiation, a 12-fold enhancement in photocatalytic activity was achieved using ZnFe2O4–TiO2 NTAs compared with TiO2 NTAs. The enhanced photogenerated electron–hole separation and improved transfer of photogenerated charge carriers were responsible for the increased photocatalytic activity of ZnFe2O4–TiO2 NTAs. This approach provides a simple method for synthesizing a variety of nanoparticle-modified one-dimensional nanomaterials. [ABSTRACT FROM AUTHOR]

Inspired by simulation analysis, we found that Cu decoration could enhance the NH 3 production rate of InVO 4 through promoting N 2 adsorption and reducing the activation energy of the key hydrogenation step. 5% Cu/InVO 4 exhibited an optimal NH 3 yield of 195.11 μmol g cat -1 h -1 , approximately six times higher than that of InVO 4 . Cu/InVO 4 was also fabricated by upcycling Cu from electroplating sludge, achieving a gratifying nitrogen fixation performance of 154.13 μmol g cat -1 h -1 .