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Structural engineering has proven effective in tailoring the photocatalytic properties of semiconductor nanostructures. In this work, a sophisticated double‐hollow yolk@shell nanostructure composed of a plasmonic, mobile, hollow Au nanosphere (HGN) yolk and a permeable, hollow CdS shell is proposed to achieve remarkable solar hydrogen production. The shell thickness of HGN@CdS is finely adjusted from 7.7, 18.4 to 24.5 nm to investigate its influence on the photocatalytic performance. Compared with pure HGN, pure CdS, a physical mixture of HGN and CdS, and a counterpart single‐hollow cit‐Au@CdS yolk@shell nanostructure, HGN@CdS exhibits superior hydrogen production under visible light illumination (λ = 400–700 nm). The apparent quantum yield of hydrogen production reaches 8.2% at 320 nm, 6.2% at 420 nm, and 4.4% at 660 nm. The plasmon‐enhanced activity at 660 nm is exceptional, surpassing the plasmon‐induced photoactivities of the state‐of‐the‐art plasmonic photocatalysts ever reported. The superiority of HGN@CdS originates from the creation of charge separation state at HGN/CdS heterojunction, the considerably long‐lived hot electrons of plasmonic HGN, the magnified electric field, and the advantageous features of double‐hollow yolk@shell nanostructures. The findings can provide a guideline for the rational design of versatile double‐hollow yolk@shell nanostructures for widespread photocatalytic applications. [ABSTRACT FROM AUTHOR]

In this work, we studied the effects of particles' size and temperature on the photoluminescence (PL) of CH3NH3PbBr3 perovskite nanocrystals (PNCs), with the PNC size controlled by varying the surface passivating ligands. The structural and optical properties of the PNCs were investigated using UV-Vis and PL spectroscopy, revealing strong quantum confinement effects. Temperature dependent PL measurements showed the spectral blue shift of the PL peak for the small PNCs (3.1 ± 0.2 nm) with decreasing temperature from 300 K to 20 K, which is opposite to the red shift with decreasing temperature observed for large- (9.2 ± 0.5 nm) and middle-sized (5.1 ± 0.3 nm) PNCs. The PL lifetime also increased with increasing temperature for the larger PNCs, while it remained about the same for the small and middle-sized PNCs. This increase in lifetime with temperature is attributed to exciton dissociation to free carriers at higher temperatures and to the formation of polar domains in the PNCs. However, the small and middle-sized PNCs did not show such a trend, which may be due to efficient defect passivation as higher concentration of 3-aminopropyl trimethoxysilane (APTMS) was used and to the role of particle size in surface state delocalization. Cryo-X-ray diffraction showed no new peak formation or peak splitting as temperature was varied, which suggests efficient crystal phase stabilization in PNCs of all three sizes controlled by the concentration of APTMS. These results emphasize the importance of size and surface properties of PNCs in their optical properties such as PL quantum yield, PL lifetime, and crystal phase stability. [ABSTRACT FROM AUTHOR]

Ammonia borane (NH 3 BH 3 , AB) is a chemical hydride with a high hydrogen capacity of 19.6 wt%, which makes it a promising hydrogen carrier. Cuprous oxide (Cu 2 O) is one of the most active photocatalysts for AB dehydrogenation at ambient conditions. However, the instability due to photocorrosion and high charge recombination are the main drawbacks of practical application. In this work, Cu 2 O is coupled with a metal-organic framework (MOF) as a composite photocatalyst (Cu 2 O/UiO-66-NH 2), which demonstrates a better photocatalytic performance in AB hydrolysis than its pure counterpart samples because of the heterojunction configuration. The Z-scheme charge transfer pathway in Cu 2 O/UiO-66-NH 2 composite can improve charge separation, hydrogen production efficiency, photocatalyst stability, and reduce activation energy. The optimum composite photocatalyst comprising 50 wt% Cu 2 O loading shows the highest hydrogen evolution yield of almost 2.3 equivalent H 2 from AB hydrolysis. [Display omitted] • Well-dispersed Cu 2 O on UiO-66-NH 2 composite for heterojunction can be reached. • Cu 2 O/UiO-66-NH 2 photocatalyzed ammonia borane hydrolysis for 2.3 eq H 2. • Low activation energy of 29.5 kJ/mol can be reached in photocatalytic AB hydrolysis. • The Cu 2 O/UiO-66-NH 2 photocatalyst demonstrated a Z-scheme charge transfer pathway. [ABSTRACT FROM AUTHOR]

Efficient glycerol electrooxidation reaction (GEOR) over gold@nickel sulfide (Au@NiSx) yolk@shell nanostructures is demonstrated, achieving ≈50.4% glycerol conversion at 10 h, 92.6% selectivity toward three‐carbon products, and 90.7% total Faradaic efficiency. By regulating the electrode potential, tartronic acid (TART), one of the highest value‐added intermediates, can be produced with a selectivity as high as 43.1% and a yield of 45.6 µmol cm−2 h−1. A combination of ex situ microstructural analysis, operando Raman, and operando X‐ray absorption measurements reveals a dynamic surface reconstruction course from Au@NiSx to Au@NiSx/NiOOH during the glycerol oxidation process. The unique reconstructed architectures featuring conductive interior NiSx components and active surface high‐valence Ni3+ species account for the superior GEOR performance. Further integration of GEOR with hydrogen evolution reaction is realized by employing Au@NiSx as both anode and cathode electrocatalysts in a two‐electrode configuration. Concomitantly production of TART and hydrogen fuel is accomplished. This study demonstrates that Au@NiSx not only can convert glycerol to TART with remarkable efficiency and selectivity, but also can produce hydrogen at a moderate level. The findings from this study can facilitate the development of dual‐functional electrocatalysts capable of producing high‐value products at both the cathode and anode sides. [ABSTRACT FROM AUTHOR]

For the first time we presented the interfacial charge carrier dynamics for three-component semiconductor-metal-semiconductor Z-scheme nanoheterostructure system. The samples were prepared by selectively depositing a thin layer of Cu 2 O on the Au surface of Au nanoparticle-decorated Na x H 2− x Ti 3 O 7 nanobelts (denoted as ST-Au NBs) using the photodeposition method. For ST-Au-Cu 2 O NB heterostructures, the embedded Au may act as carrier-transfer mediator to promote the electron transfer from the conduction band of ST to the valence band of Cu 2 O. This vectorial charge transfer would give rise to electron accumulation at Cu 2 O and hole concentration at ST, which achieved superior charge carrier separation over the two-component counterparts of ST-Au and ST-Cu 2 O. The quantum size effect was significant in the deposited Cu 2 O, which was exploited to tune the band structure of Cu 2 O, modulate the charge carrier dynamics of ST-Au-Cu 2 O NBs, and thereby enhance the resultant photocatalytic performance. Time-resolved photoluminescence spectra were measured to quantitatively analyze the electron transfer event between ST and Au for ST-Au-Cu 2 O NBs, which was found dependent on the Cu 2 O shell thickness. As the Cu 2 O thickness decreased, ST-Au-Cu 2 O NBs showed an increased electron-scavenging rate constant due to the increased driving force of electron transfer. The carrier dynamics results were fundamentally consistent with those of the performance evaluation in photocatalysis, in which ST-Au-Cu 2 O NBs exhibited enhanced photocatalytic efficiency as the Cu 2 O thickness decreased. Systematic understanding of the interfacial charge dynamics of Z-scheme mechanism shall pave the way for the realization of artificial photosynthesis by using heterogeneous photocatalysts, where the effectiveness of charge separation and the merit of high redox powers are determinant. [ABSTRACT FROM AUTHOR]

Pt-based alloy or bimetallic anode catalysts have been developed to reduce the carbon monoxide (CO) poisoning effect and the usage of Pt in direct methanol fuel cells (DMFCs), where the second metal plays a role as CO poisoning inhibitor on Pt. Furthermore, better performance in DMFCs can be achieved by improving the catalytic dispersion and using high-performance supporting materials. In this work, we introduced a free-standing, macroscopic, interwoven tubular graphene (TG) mesh as a supporting material because of its high surface area, favorable chemical inertness, and excellent conductivity. Particularly, binary AuPt nanoparticles (NPs) can be easily immobilized on both outer and inner walls of the TG mesh with a highly dispersive distribution by a simple and efficient chemical reduction method. The TG mesh, whose outer and inner walls were decorated with optimized loading of binary AuPt NPs, exhibited a remarkably catalytic performance in DMFCs. Its methanol oxidation reaction (MOR) activity was 10.09 and 2.20 times higher than those of the TG electrodes with only outer wall immobilized with pure Pt NPs and binary AuPt NPs, respectively. Furthermore, the catalyst also displayed a great stability in methanol oxidation after 200 scanning cycles, implying the excellent tolerance toward the CO poisoning effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • The band structure of CN was manipulated by doping with different elements (B, O). • The BCN/OCN was successfully synthesized by electrostatic self-assembly. • The modulated band structure improved individual oxidation/reduction capabilities. • The BCN/OCN homojunction boosts the photocatalytic hydrogen production. Photocatalytic hydrogen production is a promising method to address the increasing energy demand and depletion of fossil fuels. Among various photocatalysts, g-C 3 N 4 (CN) has attracted significant attention due to its favorable properties and tunable band structure. CN-based heterojunctions have been developed to enhance photocatalytic efficiency through improved charge separation via interfacial charge transfer. However, traditional heterojunctions formed between CN and other semiconductors often face challenges related to material compatibility and stability. In this work, we explored the formation of homojunctions, which involve identical semiconductors and offer superior charge separation and electron mobility due to perfect lattice matching. To further enhance individual oxidation and reduction capabilities, we employed band structure engineering through B doping and O doping. The homojunction between B-doped CN (BCN) and O-doped CN (OCN) was successfully synthesized using simple electrostatic self-assembly, resulting in significantly improved hydrogen production of 519.3 μmol g−1h−1 compared to BCN (34.7 μmol g−1h−1) and CN (167.2 μmol g−1h−1). This approach enhances visible light absorption, charge separation, and mobility, demonstrating the potential for developing advanced CN-based photocatalysts for various applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Using Au nanoplates in SERS sensing toward a typical PAH pollutant is demonstrated. [•] Significantly enhanced SERS activities and extremely low detection limit is achieved. [•] The SERS activity of Au nanoplates can be fully recovered after repeatedly used. [ABSTRACT FROM AUTHOR]

Atomic Pd x Au y (1 ≤ x + y ≤ 4) clusters are decorated on polyaniline to be used as the catalytic electrode in electrochemical sensors. The current responses in the oxidation of 1-propanol are used to reveal the catalytic activity. Effects of the size, decoration sequence, and composition of the atomic metal clusters decorated on the PANI on the catalytic activity are evaluated. Regarding the size, an odd-even size effect is observed in the atomic pure metal clusters, which the even-numbered pure metal clusters show a higher catalytic activity than the odd-numbered pure metal clusters. For the decoration sequence, the catalytic activity is high when the same metal is decorated in the first two cycles of the cyclic atomic electrodeposition process. For the composition effect, the atomic metal clusters show a high catalytic activity in the oxidation, in the region of second oxidation peak, when there are more Au in the atomic metal clusters. [Display omitted] • Atomic Pd x Au y (1 < x + y < 4) clusters are decorated on PANI toward 1-propanol oxidation. • Atomic pure Pd and Au clusters both show the odd-even effect. • Effects of the decoration sequence and composition are studied. • Decorating the same metal in the first 2 cycles result a better catalytic activity. • Clusters of more Pd show a low catalytic activity in the second oxidation peak. [ABSTRACT FROM AUTHOR]

Abstract: TiO2 thin films were fabricated by cathodic deposition with a supercritical CO2 (sc-CO2) emulsified TiCl3 +NaNO3 electrolyte. Morphology and average grain size were evaluated by SEM, TEM and XRD. SEM micrographs showed that the TiO2 films fabricated by TiCl3 +NaNO3 electrolyte were porous, and the films were composed of particles and aggregates of the particles. Also, size of the particles increased when the sc-CO2 emulsified electrolyte was used. Average grain size of the TiO2 films was calculated using Scherrer equation. The average grain size was found to increase when the sc-CO2 emulsified electrolyte was used. In addition, both particle sizes observed from SEM and average grain size calculated using Scherrer equation were found to increase when pressure was increased from atmospheric pressure to 20MPa. [Copyright &y& Elsevier]

Abstract: We demonstrated for the first time that Na-intercalated H2Ti3O7 (Na x H2−x Ti3O7) NBs, prepared in the typical alkaline hydrothermal process, can effectively absorb visible light to carry out photocatalytic reactions. With the capability of effective light absorption in visible range, Na x H2−x Ti3O7 NBs performed much better in the photodegradation of thionine than the other three counterpart products including H2Ti3O7, mixed Na2Ti6O13/TiO2 and anatase TiO2 under visible-light irradiations. As compared to the relevant commercial products like P-25 TiO2 and Na2Ti3O7 powders, the as-synthesized Na x H2−x Ti3O7 NBs exhibited superior photocatalytic efficiency under UV illumination, demonstrating their potential as an efficient photocatalyst in relevant redox reactions. A further enhancement in the photocatalytic activity can be achieved for Na x H2−x Ti3O7 NBs when Au nanoparticles of suitable amount were deposited on their surfaces. This improvement is due to the band offsets between Na x H2−x Ti3O7 and Au, which may promote charge carrier separation to favor the photocatalysis. The recycling test reveals that Au-decorated Na x H2−x Ti3O7 NBs could be promisingly utilized in the long-term course of photocatalysis. Furthermore, the result of performance evaluation under natural sunlight shows that the current Au-decorated Na x H2−x Ti3O7 NBs can be used as highly efficient photocatalysts which may practically harvest energy from sunlight. [Copyright &y& Elsevier]

Abstract: Tin oxide nanocrystals were successfully introduced into the mesoporous network of silica aerogels with an aqueous solution deposition process. The success of the tin oxide introduction was evidenced by the drastic reduction in the specific surface area, over 400m2/g, and pore volume of the resulted SiO2–SnO2 composite aerogels and a shift in nitrogen adsorption–desorption characteristics from type H3 to type H2 hysteresis loop of the type IV isotherm. The crystallinity of the tin oxide nanoparticles was improved and grain size was increased, from 5.5 to 8.5nm, with increasing the post-reaction thermal treatment temperature. Characterizations of photoluminescence and photocatalysis were performed, and rich photoluminescence emissions were observed. The composite aerogel showed a near band edge emission of the tin oxide nanocrystals at 349nm and two emission peaks, 318 and 475nm, attributable to the oxygen deficiency of the silica backbone. Three more emission peaks, 390, 433, 548nm, were observed, with the 390nm peak contributed by the oxygen vacancies , the 433nm peak by the Sn interstitials, and the 548nm peak by the oxygen vacancies . Photocatalysis performance of the composite aerogel was conducted for photo-degradation of methylene blue and was found achieved by the embedded tin oxide nanocrystals but not by the silica backbone. Products from three thermal treatment temperatures, 400, 500, and 700°C, were investigated, with those from thermal treatment at or above 500°C showing better performance in photocatalysis, 73% vs. 62% in conversion, attributable to the better crystallinity realized at or above 500°C. [Copyright &y& Elsevier]

A modified networks-of-zones model is developed to investigate the mixing performance of three tower-type bioreactors, namely airlift, bubble column and net column (a short notation for airlift reactor with a net draft tube) reactors. A key parameter β, that characterizes the interaction intensity between the neighboring uprising and down-coming streams, is identified to play a decisive role in determining the mixing characteristics of the three tower-type reactors. The concentration dynamics and mixing behaviors of the three types of reactor are studied with a maximum non-zero eigenvalue analysis (the slowest mode analysis). The model predictions are validated with experiments of heat mixing. The superior mixing performance of the net column reactor over the airlift and bubble column reactors is clearly revealed with the present model and is experimentally verified, and can be linked to an optimum mass transfer between the neighboring uprising and down-coming streams, provided by the net draft tube. This optimum mass transfer is a direct result of a balanced flow distribution in the axial and radial directions. [Copyright &y& Elsevier]

[Display omitted] • Strategies to adjust charge dynamics of semiconductor heterostructures are reviewed. • Precise manipulation of charge transfer dynamics is still a grand challenge. • Insights into future advancement of photocatalysis technology are summarized. As a topic of intensive research interest for decades, photocatalysis using semiconductor heterostructures holds the potential to satisfy global energy demand, reduce greenhouse effect and accomplish environmental remediation. This burgeoning technology has quickly become a high-profile emerging scientific and technological field, providing a solution to achieving sustainable development of renewables. However, critical challenges, such as inadequate solar photons absorption, mediocre charge transfer dynamics, poor surface reaction kinetics and lack of long-term stability, have hindered the widespread deployment of semiconductor photocatalysts. Interfacial charge dynamics is particularly relevant to the utility of photocatalysis because it dictates charge transfer and carrier utilization, the two complicated yet key processes involved in the photocatalytic reactions. The means to modulating charge dynamics and even manipulating carrier behavior may pave a new avenue for intelligent design of versatile photocatalysts for advanced applications. This review introduces the recent development on conceptual strategies and experimental approaches that can be exploited to modulating charge dynamics of semiconductor heterostructures for maximizing carrier utilization efficiency. New insights into the future advancement of photocatalysis technology based on the adoption of the proposed tactics are also discussed and summarized. [ABSTRACT FROM AUTHOR]

• The NVCN was successfully synthesized by thermal treatment using NaBH 4. • The band structure was further manipulated by altering the calcination temperature. • The modulated band structure suppressed charge recombination. • The incorporation of NVs and B dopants synergistically boosts the PcNRA process. Photocatalytic nitrate reduction to ammonia (PcNRA) not only tackles nitrate pollution in wastewater but also transforms it into valuable ammonia, attracting attention as an eco-friendly and carbon-free ammonia synthesis technology. However, it still suffers from insufficient ammonia selectivity due to active side reactions such as nitrogen gas formation and hydrogen production. In this work, we synthesized B-doped and N-deficient g-C 3 N 4 (NVCN) by thermal treatment using NaBH 4 as a reduction reagent for selective photocatalytic nitrate-ammonia conversion. The simultaneous introduction of B dopants and nitrogen vacancies (NVs) into the g-C 3 N 4 (CN) framework modulated the band structure: the narrowed band gap and the generated mid-gap states suppressed charge carrier recombination and allowed more electrons to participate in the reduction reaction, while the reduced conduction band energy effectively inhibited hydrogen evolution, defining possible reaction pathways to nitrate reduction. Moreover, nitrate species were strongly adsorbed and activated on the catalyst surface in the co-presence of B dopants and NVs, which consequently facilitated selective and active nitrate-to-ammonia conversion. The optimal catalyst, NVCN475, achieved exceptional ammonia selectivity (96.9 %) and production activity (8.83 μmol h−1) with negligible H 2 evolution (0.52 μmol h−1) under visible light irradiation. [ABSTRACT FROM AUTHOR]

Photocatalytic nitrate (NO 3 ) reduction to NH 3 (PcNRA) is a sustainable alternative that is considered advantageous over N 2 fixation, which suffers from the high dissociation energy and sluggish activation of inactive N 2. Although PcNRA has recently been shown to achieve excellent selectivity, its sluggish kinetics restrict the NH 3 production efficiency. Herein, we present a single-atom Cu-incorporated TiO 2 nanosheet (Cu-TNS) photocatalyst for efficient and selective PcNRA. Single Cu atoms displacing Ti sites accumulate photogenerated electrons, ensuring efficient charge separation and surface NO 3 reduction. Moreover, introducing Cu atoms into the TiO 2 matrix induces spontaneous defect formation, resulting in oxygen vacancies and lattice strain that promote NO 3 adsorption and activation. The simultaneous presence of single Cu atoms and structural defects in Cu-TNS synergistically stimulates PcNRA, leading to a 62-fold enhancement over pristine TiO 2 in NH 3 production with 97.6% selectivity and an unprecedently high apparent quantum yield of 11.7% at 330 nm under optimized conditions. [Display omitted] • We demonstrate the impressive impact of single-atom catalyst for photocatalytic NO3 reduction to NH3. • Isolated Cu atoms effectively accumulate photoelectrons, suppressing charge recombination. • Spontaneously configured structural defects promote NO3 adsorption and activation. • An unprecedently high apparent quantum yield of 11.7% at 330 nm is achieved under optimal conditions. [ABSTRACT FROM AUTHOR]

In the present work, we improved the photoelectrochemical (PEC) performance of tungsten trioxide (WO 3) photoanode by decorating WO 3 plates with Au nanoplates. WO 3 plates were fabricated on FTO-coated glass by hydrothermal treatment and Au nanoplates were incorporated by immersing the substrates in Au nanoplates solution under different periods of time. Our study revealed that compared with pristine WO 3 , the Au-WO 3 nanocomposite performed enhanced photocurrent density under irradiation of the simulated sunlight. This improved PEC performance was benefited from the extension of light absorption resulting from the surface plasmon resonance effect of Au nanoplates at about 650 nm wavelength, and it was verified by UV–vis absorption spectra. The incident photon-to-current conversion efficiency measurements revealed improved photoactivity after decoration of WO 3 with Au nanoplates. This study provided a facile method to decorate Au nanoplates on WO 3 photoanodes with enhanced performance for solar energy conversion. Image 1 • Au-WO 3 photoanodes were fabricated by simply immersing WO 3 in Au nanoplates solution. • Surface plasmon resonance of Au nanoplates resulted in enhanced light absorption. • With Au nanoplates decoration, the photoactivity was improved under simulated sunlight. • The improved photoelectrochemical properties of Au-WO 3 photoanodes were studied. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Au@Cu 2 O works as dual-functional catalyst for sustainable E. coli inactivation. • Peroxidase activity of Au@Cu 2 O increases with increasing shell thickness. • Pronounced charge separation promotes photocatalysis for Au@Cu 2 O. • Continuous operation under illumination and darkness conditions is demonstrated. Abstract This work reports the synthesis of Au@Cu 2 O core@shell nanocrystals with controllable shell thicknesses and demonstrates their use as the dual-functional catalyst that can continuously operate under illumination and darkness conditions for efficient E. coli inactivation. On account of the peroxidase mimics of the Au core and Fenton reactivity of the Cu 2 O shell, the Au@Cu 2 O nanocrystals exhibit intrinsic peroxidase-like property with the reaction kinetics in accordance with the typical Michaelis–Menten mechanism. On the other hand, time-resolved photoluminescence spectra suggest the prevalence of pronounced charge separation for Au@Cu 2 O nanocrystals, an important advantage that is favourable for photocatalysis. By combining the photocatalytic capability with the peroxidase mimics features, Au@Cu 2 O nanocrystals can perform practical photocatalytic decomposition of E. coli under visible light illumination but still show vital activity towards E. coli inactivation after light illumination was turned off. The current study delivers a new catalyst configuration by exploiting the multiple functionalities of nanosized Au and Cu 2 O for advanced environmental and energy conversion applications. [ABSTRACT FROM AUTHOR]

This work reports the novelty of using eco-friendly and cost-effective non-vacuum Electrostatic Spray-Assisted Vapour Deposited Cu(In,Ga)SSe (CIGS) thin films as photocathodes, combined with the earth abundant cobalt sulfide (Co–S) as a catalyst to accelerate the kinetics of photogenerated electron transfer and hydrogen generation for photoelectrochemical water splitting. CdS and ZnO layers were subsequently deposited on top of the selenised CIGS films to increase the charge separation and lower the charge recombination for the photocathodes. In order to improve the lifetime and scalability of the CIGS photocathode and the other cell components, a photoelectrochemical test was conducted in a neutral electrolyte of 0.5 M Na2SO4 under simulated sunlight (AM 1.5G). Both the photocurrent densities and the onset potentials of the photocathodes were significantly improved by the electrodeposition of the low cost and earth-abundant Co–S catalyst, with a photocurrent density as high as 19.1 mA cm−2 at −0.34 V vs. reversible hydrogen electrode (RHE), comparable with and even higher than that of the control photocathode using rare and precious Pt as a catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • Use ALD and hydrothermal method to attach ZnO branched nanorods to TiO 2 nanorod arrays on FTO substrate. • Incorporate Au triangular nanoplates (TNP) with ZnO@TiO 2 by immersing samples in Au TNP solution. • 3D ZnO provides more reactive sites, facilitates interfacial charge transfer and promotes efficient separation of photogenerated electron-hole pairs. • Surface plasmon resonance of Au TNP amplifies the local electromagnetic field and enhances light harvesting. • Improved photoelectrochemical properties of Au@ZnO@TiO 2 ternary heterostructure system are obtained. Transition metal-oxide semiconductors have shown great potential in the renewable energy harvesting and conversion, e.g., photoelectrochemical (PEC) water splitting. However, the existing disadvantages of semiconductors, such as insufficient solar light utilization and fast charge recombination, are urgently needed to be addressed to realize an efficient PEC device. In this work, we synthesized a well-defined ZnO branched nanorods (b-NRs) attached to TiO 2 nanorod (NR) arrays on FTO substrate using atomic layer deposition (ALD) and hydrothermal method. Meanwhile, Au triangular nanoplates (TNPs) were also incorporated with ZnO@TiO 2 heterostructure by immersing the structure in Au TNPs solution. The ZnO b-NRs@TiO 2 NRs and Au TNPs@ZnO b-NRs@TiO 2 NRs exhibited the photocurrent densities of 0.490 mA/cm2 and 0.733 mA/cm2 at 1.23 V vs. reversible hydrogen electrode which were 2.8 and 4.2 times of pure TiO 2 NR arrays (0.176 mA/cm2), respectively. Incident photon-to-current conversion efficiency measurements showed enhanced photoactivity after Au TNPs decoration. Moreover, the electrochemical impedance spectroscopy and Mott-Schottky analysis provided further evidence that the separation of photogenerated carriers and the transfer kinetics of charge carriers at the semiconductor/electrolyte interface were greatly improved by the ZnO b-NRs modification and Au TNPs decoration. It was concluded that the significantly enhanced PEC water splitting performance was attributed to the synergistic effect of the three-dimensional ZnO@TiO 2 composites heterostructure and the localized surface plasmon resonance resulting from Au TNPs. This study reported a facile combination of ALD and hydrothermal method for fabricating ZnO branched heterostructure and decorating Au TNPs to improve the PEC water splitting performance of TiO 2. [ABSTRACT FROM AUTHOR]

In this study, we have synthesized CdS/CdSe co-sensitized brookite TiO 2 nanostructures with hydrogen doping (H:TiO 2 /CdS/CdSe) in a facile solution reaction and studied their PEC performances. Compared to undoped brookite TiO 2 , the H:TiO 2 /CdS/CdSe composites exhibit much enhanced photocurrent generation, which originates from the improved charge transfer kinetics endowed by hydrogen doping and sensitization. Time-resolved photoluminescence (PL) and electrochemical impendence spectroscopy (EIS) are employed to explore the charge transfer dynamics between sensitizers and TiO 2 and charge carrier kinetics at the semiconductor/electrolyte interface. According to the analytical results, sensitizations of TiO 2 are found to enhance the charge separation efficiency. Besides, the hydrogen doping into TiO 2 generates oxygen vacancy states, providing additional charge transfer pathway and prohibiting charge recombination, beneficial for enhancing the PEC performances as well. Based on the charge dynamics data, we further develop charge transfer models for TiO 2 /CdS/CdSe and H:TiO 2 /CdS/CdSe. The findings from this work can help understanding the charge transfer dynamics in brookite TiO 2 -based composite systems as well as designing versatile photoelectrodes for solar energy conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Origin of MnO x co-catalysts for improved PEC properties of Fe 2 O 3 is revealed. • MnO x promotes charge separation and induces anodic shift of valence band. • Introducing MnO x enhances electrochemical active sites as well. • Negative backward charge transfer occurs as excess amount of MnO x is introduced. Fe 2 O 3 is a promising photoanode towards photoelectrochemical (PEC) reactions, but its efficiency is hampered by poor charge transfer dynamics and sluggish surface reaction kinetics. To resolve these issues, surface modification with co-catalysts has been widely adopted. Among different co-catalysts, MnO x has been considered as a particularly appealing candidate for PEC performance optimization of Fe 2 O 3. However, the origin of MnO x co-catalysts has been ambiguous, making its widespread employment stagnating. Herein, the influence of introducing amorphous MnO x co-catalysts on the PEC performance of Fe 2 O 3 has been systematically investigated. Analytical results reveal that the introduced MnO x not only promotes charge transfer dynamics of Fe 2 O 3 , induces anodic shift of valence band, but also functions as electrochemical active sites to facilitate surface reaction kinetics. The present study has successfully delivered mechanistic understanding of the function of MnO x co-catalysts, and provided a rational design strategy to maneuver Mn-based co-catalysts for improving PEC performance of semiconductor photoanodes. [ABSTRACT FROM AUTHOR]

The use of Au@Cu 2 O core@shell nanocrystals as sustainable catalysts for efficient hydrogen (H 2) production from ammonia borane (AB) is demonstrated. By combining the attributes associated with core@shell structural features and electronic interactions, Au@Cu 2 O exhibited remarkable performance toward AB hydrolysis. The effect of shell thickness on H 2 production performance was systematically investigated. Results showed that H 2 production rate increased monotonically with shell thickness, while degree of dehydrogenation of AB was subject to optimization by shell thickness. A maximal 3.0 equivalents of H 2 production can be achieved by Au@Cu 2 O with an optimal Cu 2 O shell thickness. The H 2 produced from AB hydrolysis on Au@Cu 2 O was introduced to power a fuel cell for lightening light emitting diodes. The findings from the work not only enrich the family of metal/metal oxide composite catalysts for AB hydrolysis, but also deepen the fundamental understanding of implications of core@shell structural features and electronic interactions in dehydrogenation of AB. [Display omitted] • Au@Cu 2 O catalyses efficient H 2 production from ammonia borane. • H 2 production rate increases monotonically with increasing shell thickness. • Degree of dehydrogenation of AB is subject to optimization by shell thickness. • 3.0 equivalents of H 2 production is achieved at an optimal shell thickness. • Produced H 2 is introduced to power a customized fuel cell for lightening LEDs. [ABSTRACT FROM AUTHOR]

We demonstrated a facile and green preparation of cuprous oxide-reduced graphene oxide (Cu 2 O-rGO) nanoheterostructures through a photochemical reaction. The density of Cu 2 O nanocubes (NCs) grown on the rGO surface can be well controlled by modulating the concentration of GO employed in the reaction. Because of the relatively low potential of Fermi level of rGO, the photoexcited electrons on the conduction band (CB) of Cu 2 O NCs preferentially transfer to rGO, simultaneously leaving photogenerated holes on the valence band (VB) of Cu 2 O, resulting in the notable charge carrier separation properties. Time-resolved photoluminescence (TRPL) spectra were collected to quantitatively analyze the electron transfer rate constant ( k et ) between Cu 2 O NCs and rGO, and the dependence of the k et on the rGO constituent in Cu 2 O-rGO nanoheterostructures. Among all the samples tested, the Cu 2 O-rGO nanoheterostructure with the rGO constituent of 2 wt.% (denoted as Cu 2 O-rGO-2) displayed the largest k et as well as the most pronounced charge separation property. The optimized Cu 2 O-rGO-2 showed the best methyl orange (MO) photocatalytic degradation performance, which was highly consistent with the trend of the obtained k et results. As compared with relevant commercial products, such as N-doped P-25 TiO 2 and commercial Cu 2 O powders, the Cu 2 O-rGO-2 exhibited superior efficiency toward MO degradation under visible light illumination, illustrating its potential for applications in relevant photoelectric conversion processes. The recycling trial showed that the Cu 2 O-rGO-2 has promising potential for use in the long-term course of photocatalysis to degrade organic pollutants. Furthermore, the photocatalytic efficiency evaluated under natural sunlight demonstrated that the present Cu 2 O-rGO nanoheterostructure could effectively harvest the energy of solar spectrum and converted it into the chemical energy for organic pollutants degradation. The current study could provide great insights into the design of semiconductor/graphene composites which exhibit remarkable charge separation properties for practical applications in the organic pollutants photodegradation, solar fuel generation as well as photovoltaic devices. [ABSTRACT FROM AUTHOR]

This study reports the effect of the high pressure on properties, especially the crystallinity, of the TiO 2 and SnO 2 films cathodically deposited in supercritical CO 2 emulsified electrolyte. The as-deposited metal oxides are usually amorphous when cathodic deposition is applied. An additional heat treatment process is needed to have crystalline metal oxides. In this study, the TiO 2 and SnO 2 thin films cathodically deposited at elevated pressure showed an improvement in the crystallinity with an increase in the pressure using X-ray diffraction analysis. The high-resolution transmission electron microscopy and selected-area electron diffraction confirmed that the TiO 2 deposited at 35 MPa had the anatase crystal structure. An enhancement in the charge carrier dynamics at the TiO 2 electrode/electrolyte interface with an increase in the pressure was observed from the electrochemical impedance spectroscopy, which is a result of the improved crystallinity. The effect of the pressure on the crystallinity of the SnO 2 was more obvious than that on the TiO 2 . Grain size of the SnO 2 films estimated by the Scherrer equation was increased from 3.5 to 14.8 nm when the pressure was increased from 5 to 25 MPa. [ABSTRACT FROM AUTHOR]

We reported for the first time that GaOOH nanorods, which were prepared using a facile chemical precipitation method, may display noticeable photocatalytic activities toward methanol oxidation under light illumination, a significant revelation for demonstrating their use as the anode photocatalyst in the half-cell reaction of direct methanol fuel cells (DMFCs). The GaOOH nanorods were further decorated with Au nanoparticles to endow them with increasingly pronounced charge separation, which conduced to a remarkable enhancement in the photocatalytic performance. Time-resolved photoluminescence spectroscopy was employed to depict the charge transfer event across the interface of GaOOH/Au, from which a correlation between photocatalytic efficiency and interfacial charge dynamics was realized. By incorporating GaOOH nanorods into the traditional Pt-catalyzed half-cell reaction, a 12.7% increase in anodic current generation can be attained under light illumination, demonstrating the promising potential of GaOOH as a practical anode photocatalyst in DFMCs. A further enhancement in methanol oxidation current up to 70.8% can be achieved by employing Au-decorated GaOOH nanorods, which was attributed to the efficient charge carrier transfer rendered by the Au decoration. The current study delivers both fundamental and practical importance as it broadens the scope of electrocatalysts for fuel cells, specifically by introducing a new class of highly efficient photocatalysts for promoting electrochemical reactions. [ABSTRACT FROM AUTHOR]

With exciting functionality, topological defects in ferroic system have attracted significant attention. Under proper design, the emergence of polar domain walls in non-polar ferroelastics enables a flexo-phototronic effect. In this study, we revealed ferroelastic twin texture with localized flexoelectric effect in centrosymmetric epitaxial BiVO 4 film. Supported by photodeposition and localized photocurrent analysis, we found the flexoelectric effect confined at domain wall area facilitates the photocarrier transport and the flexo-phototronic mechanism was further supported by dye-degradation and generation of reactive radicals. This work not only provides new insights into the introduction of flexo-phototronic effects in non-polar materials, but also sheds light on the use of material inhomogeneity for acquiring multifunctionality. [Display omitted] • Centrosymmetric BiVO 4 thin film with initial polar domain walls were fabricated. • The flexo-potential promotes photo-induced carrier separation and endows flexo-catalytic effect in centrosymmetric BiVO 4. • The flexo-catalytic effect is further demonstrated in another centrosymmetric system WO 3. [ABSTRACT FROM AUTHOR]

A facile, green one-pot hydrothermal method has been developed to prepare ZnO-reduced graphene oxide (rGO) composites with controllable rGO content. Time-resolved photoluminescence spectra revealed that an increased electron-transfer rate constant was observed for ZnO–rGO with increasing rGO contents, suggesting that an increased number of photoexcited charge carriers were separated and available for photocatalysis utilization. The photocatalytic properties of the ZnO–rGO composites were investigated by using gaseous acetaldehyde (CH 3 CHO), a typical volatile organic compound (VOC), as the test pollutant. This is the first time that ZnO–rGO composites have been used as photocatalysts for gaseous CH 3 CHO degradation. Compared to pure ZnO, ZnO–rGO composites with suitable rGO contents (1.0 and 3.0 wt%) displayed significantly enhanced photocatalytic activity in both CH 3 CHO degradation and CO 2 generation. This enhancement was ascribed to the rGO support that can promote the carrier utilization efficiency of ZnO by readily accepting the photoexcited electrons from ZnO. As a result, abundant photogenerated holes remained on the ZnO and were available for participation in the CH 3 CHO photodegradation. Furthermore, the photoactivity of ZnO–rGO toward electrolytic water oxidation was evaluated. The results showed that ZnO–rGO composites achieved 50% increase in water oxidation current over pure ZnO under white light illumination. The demonstration from this work may facilitate the use of ZnO–rGO composites in photodegradation of VOCs as well as for photoelectrochemical applications, which is imperative from the environmental and energetic points of view. [ABSTRACT FROM AUTHOR]

Highlight: [•] We successfully yield the core-shelled SiO2–Ag nanospheres. [•] Proof the Ag shell's size effect the SPR conditions. [•] Enhancing the degradation efficiency is controlled by Ag nanoparticles’ size. [•] We replaced the formaldehyde and ammonia with glucose as the reduction in seed-mediated process. [ABSTRACT FROM AUTHOR]

Highlights: [•] The concept of rainbow photocatalysts was realized by assembling Cd1-x Zn x Se NRs. [•] A remarkable photoconversion efficiency was observed under white light illumination. [•] The broadband light absorption of NRs assembly enables full visible light harvesting. [•] The NRs assembly can be used for efficient solar fuel production. [ABSTRACT FROM AUTHOR]

An unstoichiometric H-ZnO 1- x surface with oxygen vacancies and the enriched photohole reservoir in carboxyl-conjugated CQD were great benefit to govern the rate of internal and interfacial charge separation and transport in CQD/H-ZnO 1- x /ZnO multijunction. In this system, an extraordinary photocurrent density of 4.5 mA∙cm–2 was achieved and maintained cycling stability with only a 4.9 % reduction after operation of 24 h. • H-ZnO 1- x /ZnO was studied computationally and experimentally. • CQDs with loaded H-ZnO 1- x /ZnO boosted photocatalytic H 2 production. • Superiority of CQD/H-ZnO 1- x /ZnO results from the improved charge transfer. • Unusual activity and vigorous stability were obtained. • The multiple effect was investigated with soft XAS in situ and TRPL. A well-steered coordination environment on photoelectrode can offer fruitful active sites and efficaciously alter atomic and electronic configuration to boost the performance in water oxidation. To enhance the performance of the photocatalytic oxygen-evolution reaction, enriched oxygenous-type carbon quantum dots (CQD) were combined with oxygen-deficient ZnO@H-ZnO 1- x homojunctions for the first time. Specifically, hydrogenation created an unstoichiometric H-ZnO 1- x surface through oxygen vacancies, which were responsible for the formation of coordinatively unsaturated Zn centers to drive the photoelectrochemical reaction by precise regulation of the charge density, valence-band edge, atomic geometric structure and electronic structure. The enriched photohole reservoir in carboxyl-conjugated CQD was a great benefit for super-rapid charge tunnels, thereby governing the rate of internal and interfacial charge separation and transport in the multijunction. Accordingly, the CQD/H-ZnO 1- x /ZnO photoanodes showed a photoactivity enhanced five-fold relative to bare ZnO NR and maintained that high performance for 24 h of operation. Comprehensive analyses, involving electrochemical measurements, time-resolved photoluminescence, X-ray absorption spectra in situ and calculations with density-functional theory were undertaken to elucidate the underlying mechanism of enhancement and the route of directional charge transport as well as the interfacial charge dynamics over the CQD/H-ZnO 1- x /ZnO photoelectrode. These findings provide a new track towards photoelectrodes that could yield not only strikingly enhanced photocatalysis but also satisfied stability for realistic application. [ABSTRACT FROM AUTHOR]

Due to its low cost, environmentally friendly process, and lack of secondary contamination, the photodegradation of dyes is regarded as a promising technology for industrial wastewater treatment. This technology demonstrates the light-enhanced generation of charge carriers and reactive radicals that non-selectively degrade various organic dyes into water, CO2, and other organic compounds via direct photodegradation or a sensitization-mediated degradation process. The overall efficiency of the photocatalysis system is closely dependent upon operational parameters that govern the adsorption and photodegradation of dye molecules, including the initial dye concentration, pH of the solution, temperature of the reaction medium, and light intensity. Additionally, the charge-carrier properties of the photocatalyst strongly affect the generation of reactive species in the heterogeneous photodegradation and thereby dictate the photodegradation efficiency. Herein, this comprehensive review discusses the pseudo kinetics and mechanisms of the photodegradation reactions. The operational factors affecting the photodegradation of either cationic or anionic dye molecules, as well as the charge-carrier properties of the photocatalyst, are also fully explored. By further analyzing past works to clarify key active species for photodegradation reactions and optimal conditions, this review provides helpful guidelines that can be applied to foster the development of efficient photodegradation systems. [ABSTRACT FROM AUTHOR]

Near infrared energy remains untapped toward the maneuvering of entire solar spectrum harvesting for fulfilling the nuts and bolts of solar hydrogen production. We report the use of Au@Cu 7 S 4 yolk@shell nanocrystals as dual-plasmonic photocatalysts to achieve remarkable hydrogen production under visible and near infrared illumination. Ultrafast spectroscopic data reveal the prevalence of long-lived charge separation states for Au@Cu 7 S 4 under both visible and near infrared excitation. Combined with the advantageous features of yolk@shell nanostructures, Au@Cu 7 S 4 achieves a peak quantum yield of 9.4% at 500 nm and a record-breaking quantum yield of 7.3% at 2200 nm for hydrogen production in the absence of additional co-catalysts. The design of a sustainable visible- and near infrared-responsive photocatalytic system is expected to inspire further widespread applications in solar fuel generation. In this work, the feasibility of exploiting the localized surface plasmon resonance property of self-doped, nonstoichiometric semiconductor nanocrystals for the realization of wide-spectrum-driven photocatalysis is highlighted., (© 2024. The Author(s).)

Compared to other known materials, metal-organic frameworks (MOFs) have the highest surface area and the lowest densities; as a result, MOFs are advantageous in numerous technological applications, especially in the area of photocatalysis. Photocatalysis shows tantalizing potential to fulfill global energy demands, reduce greenhouse effects, and resolve environmental contamination problems. To exploit highly active photocatalysts, it is important to determine the fate of photoexcited charge carriers and identify the most decisive charge transfer pathway. Methods to modulate charge dynamics and manipulate carrier behaviors may pave a new avenue for the intelligent design of MOF-based photocatalysts for widespread applications. By summarizing the recent developments in the modulation of interfacial charge dynamics for MOF-based photocatalysts, this minireview can deliver inspiring insights to help researchers harness the merits of MOFs and create versatile photocatalytic systems., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A Z-scheme heterojunction with spatially separated cocatalysts is proposed for overcoming fundamental issues in photocatalytic water splitting, such as inefficient light absorption, charge recombination, and sluggish reaction kinetics. For efficient light absorption and interfacial charge separation, Z-scheme organic/inorganic heterojunction photocatalysts are synthesized by firmly immobilizing ultrathin g-C 3 N 4 on the surface of TiO 2 hollow spheres via electrostatic interactions. Additionally, two cocatalysts, Pt and IrO x , are spatially separated along the Z-scheme charge-transfer pathway to enhance surface charge separation and reaction kinetics. The as-prepared Pt/g-C 3 N 4 /TiO 2 /IrO x (PCTI) hollow sphere photocatalyst exhibits an exceptional H 2 evolution rate of 8.15 mmol h -1 g -1 and a remarkable apparent quantum yield of 24.3% at 330 nm in the presence of 0.5 wt% Pt and 1.2 wt% IrO x cocatalysts on g-C 3 N 4 and TiO 2 , respectively. Photoassisted Kelvin probe force microscopy is used to systematically analyze the Z-scheme charge-transfer mechanism within PCTI. Furthermore, the benefits of spatially separating cocatalysts in the PCTI system are methodically investigated in comparison to randomly depositing them. This work adequately demonstrates that the combination of a Z-scheme heterojunction and spatially separated cocatalysts can be a promising strategy for designing high-performance photocatalytic platforms for solar fuel production., (© 2022 Wiley-VCH GmbH.)

In this work, we develop a wireless sensor-integrated face mask using Au@SnO 2 nanoparticle-modified conductive fibers based on augmented reality (AR) technology. AR technology enables the overlay of real objects and environments with virtual 3D objects and allows virtual interactions with real objects to create desired meanings. With the help of the AR system, the size of the mask could be precisely estimated and then manufactured using 3D printing technology. The body temperature sensor and respiratory sensor were integrated into the mask so that vital parameters of the human body could be continuously monitored without removing the personal protective equipment. Furthermore, the outer part of the mask consists of conductive fabric modified with Au@SnO 2 core-shell nanoparticle additives, which enhanced the filtration efficiency of airborne aerosols. A significant improvement in the filtration efficiency of particulate matter 2.5 was observed after applying an external voltage to the conductive textiles. A smartwatch with a heart rate sensor was paired with the mask to display sensor data on the mask through wireless transmission. Therefore, this sensor-integrated mask system with AR technology provides the first line of defense to combat global threats from pathogens and air pollutants., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

In this work, we demonstrated the practical use of Au@Cu 2 O core-shell and Au@Cu 2 Se yolk-shell nanocrystals as photocatalysts in photoelectrochemical (PEC) water splitting and photocatalytic hydrogen (H 2 ) production. The samples were prepared by conducting a sequential ion-exchange reaction on a Au@Cu 2 O core-shell nanocrystal template. Au@Cu 2 O and Au@Cu 2 Se displayed enhanced charge separation as the Au core and yolk can attract photoexcited electrons from the Cu 2 O and Cu 2 Se shells. The localized surface plasmon resonance (LSPR) of Au, on the other hand, can facilitate additional charge carrier generation for Cu 2 O and Cu 2 Se. Finite-difference time-domain simulations were carried out to explore the amplification of the localized electromagnetic field induced by the LSPR of Au. The charge transfer dynamics and band alignment of the samples were examined with time-resolved photoluminescence and ultraviolet photoelectron spectroscopy. As a result of the improved interfacial charge transfer, Au@Cu 2 O and Au@Cu 2 Se exhibited a substantially larger photocurrent of water reduction and higher photocatalytic activity of H 2 production than the corresponding pure counterpart samples. Incident photon-to-current efficiency measurements were conducted to evaluate the contribution of the plasmonic effect of Au to the enhanced photoactivity. Relative to Au@Cu 2 O, Au@Cu 2 Se was more suited for PEC water splitting and photocatalytic H 2 production by virtue of the structural advantages of yolk-shell architectures. The demonstrations from the present work may shed light on the rational design of sophisticated metal-semiconductor yolk-shell nanocrystals, especially those comprising metal selenides, for superior photocatalytic applications.