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The construction of efficient semiconductor/cocatalyst heterojunction is a promising strategy to promote the photocatalytic H 2 -production efficiency from water reduction. Herein, a novel Cu 2 (OH) 2 CO 3 /Zn 0.5 Cd 0.5 S heterojunction composite with superior photocatalytic H 2 -generation activity and stability was prepared via a facile in situ synthetic route, in which Cu 2 (OH) 2 CO 3 served as cocatalyst stimulating the photocatalytic H 2 -evolution performance of Zn 0.5 Cd 0.5 S. The Cu 2 (OH) 2 CO 3 /Zn 0.5 Cd 0.5 S heterojunction photocatalyst containing 5 wt% of Cu 2 (OH) 2 CO 3 exhibited a prominent H 2 -evolution efficiency of 275.7 μmol h−1, which is superior to the noble metal Pt-modified Zn 0.5 Cd 0.5 S photocatalyst (237.3 μmol h−1) and much higher than bare Zn 0.5 Cd 0.5 S (90.8 μmol h−1). The active Cu+/Cu0 species generated during the photoreaction process is responsible for the prominent H 2 -production activity of the heterojunction photocatalyst, which plays triple roles in enhancing the photoactivity of Zn 0.5 Cd 0.5 S via accelerating the charge separation, decreasing the overpotential of H 2 -generation and improving the reduction ability of photoinduced electrons. Moreover, the formed Cu+/Cu0 species during photoreaction can be readily oxidized back to Cu 2 (OH) 2 CO 3 upon exposure to air, thus restores the photoactivity and therefore enables good reusability of the Cu 2 (OH) 2 CO 3 /Zn 0.5 Cd 0.5 S heterojunction photocatalysts. This work provides a new insight into the fabrication of Cu 2 (OH) 2 CO 3 -assisted heterojunction photocatalysts with the highly stable and efficient performances for solar-to-chemical energy conversion. Unlabelled Image • A novel binary Cu 2 (OH) 2 CO 3 /Zn 0.5 Cd 0.5 S composite was successfully synthesized. • The trifunctional roles of Cu 2 (OH) 2 CO 3 cocatalyst were discussed. • Mechanism of the enhanced photocatalytic activity was illuminated. [ABSTRACT FROM AUTHOR]

Magnetic Bi 2 O 2 CO 3 /ZnFe 2 O 4 heterojunction photocatalysts with varying content of ZnFe 2 O 4 were constructed by modifying Bi 2 O 2 CO 3 nanosheets with mesoporous ZnFe 2 O 4 nanoparticles. The photoactivity of the products was investigated by decomposing RhodamineB (RhB) and it was found that the photoactivity of Bi 2 O 2 CO 3 /ZnFe 2 O 4 composite was closely related to the loading amount of ZnFe 2 O 4 . Under simulant sunlight irradiation, the optimum photoactivity of Bi 2 O 2 CO 3 /ZnFe 2 O 4 composite was almost 2.3 and 2.1 times higher than that by bare ZnFe 2 O 4 and Bi 2 O 2 CO 3 , respectively. The improved photoactivity resulted from the synergistic effect of Bi 2 O 2 CO 3 and ZnFe 2 O 4 , which not only extended the photoabsorption region but also significantly facilitated the interfacial charge transfer. Besides the high photocatalytic performance, Bi 2 O 2 CO 3 /ZnFe 2 O 4 composite also exhibited excellent stable and recycling properties, which enabled it have great potential in a long-term practical use. [ABSTRACT FROM AUTHOR]

The photodegradation of organic pollutants is an attractive green chemistry technology for water pollution control. Here we prepared a new composite material consisting of BiPO 4 nanocrystals grown on layered graphene and MoS 2 as a high-performance photocatalyst for the photodegradation of organic pollutants. This composite material was synthesized by a facile one-pot microwave-assisted hydrothermal technique in the presence of layered graphene and MoS 2 . Through optimizing the loading content of each component, the BiPO 4 -MoS 2 /graphene nanocomposite exhibited the highest photocatalytic activity for the degradation of Rhodamine (RhB) when the content of MoS 2 and graphene was 2 wt% and 7 wt%, respectively. The enhanced photocatalytic activity of the new composite photocatalyst was attributed to the positive synergetic effect of the layered graphene and MoS 2 as cocatalyst, which acted as electron collector and transporter for the interfacial electron transfer from BiPO 4 to electron acceptor in the aqueous solution and thus suppressed the charge recombination and made the photogenerated holes more available to participated in the oxidation process. Moreover, the presence of layered MoS 2 /graphene hybrid could offer more reactive sites and activated the O 2 molecular in water to form superoxide radical, thereby resulting in the enhanced photocatalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: The evolution of alumina coating layers on rutile TiO2 particle surfaces was investigated starting from aluminum sulfate by a chemical liquid deposition method. The morphology of the alumina coating layers was determined by transmission electron microscopy. The chemical structure and the evolution mechanism of the alumina coating layers on TiO2 surfaces were investigated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and powder X-ray diffraction techniques. The dispersibility of the alumina-coated TiO2 powders was determined by dynamic laser scattering (DLS) mode. The alumina coating layers existed in boehmite phase, AlOOH, and anchored at the surfaces of TiO2 via Ti–O–Al bond. The formation of alumina coating layers on TiO2 surfaces depended on the pH value of the deposition solution and the alumina loading. After coated by alumina layer, the dispersibility, whiteness, brightness, and light scattering index of the resultant samples were promoted. [Copyright &y& Elsevier]

Abstract: SiO2-coated TiO2 powders were prepared by the chemical deposition method starting from rutile TiO2 and Na2SiO3. The SiO2-coated TiO2 powders were characterized by X-ray photoelectron spectroscopy, Zeta-potential analysis, Fourier transform infrared spectroscopy, and transmission electron microscopy. The evolution of island-like and uniform coating layers was found to depend upon the ratio of Na2SiO3 to TiO2, reaction temperature, and pH. The whiteness and brightness of the SiO2-coated TiO2 powders increased in response to an increase in the SiO2 loading, but there was a maximum value among the light scattering indexes. The SiO2-coated TiO2 powders possessed more negative Zeta potentials than the naked TiO2. The dispersibility of the SiO2-coated TiO2 powders with the continuous and uniform SiO2 coating layers was higher than that of the naked TiO2 and the SiO2-coated TiO2 powders with the island-like SiO2 coating layers. [Copyright &y& Elsevier]

• Mn 0.5 Cd 0.5 S decorated with Au and MoO 2 dual cocatalysts synthesized for H 2 -production. • Synergetic effects between the multifunctional Au NPs and MoO 2 cocatalysts discussed. • High H 2 -production rate achieved over composite, 3.73 folds higher than Mn 0.5 Cd 0.5 S. The construction of semiconductor-based nanoheterostructures toward achieving high efficient solar-to-fuel conversion is greatly limited by the insufficient electron-hole separation and the narrow spectrum range of light absorption. In this work, a novel Mn 0.5 Cd 0.5 S solid solution decorated with robust and multifunctional MoO 2 and Au nanoparticles (NPs) has been constructed by a facile two-step route: the deposition of Au NPs via an in situ deposition route and further loading of MoO 2 via an ultrasonic chemical method. Characterization results show that both MoO 2 and Au NPs can be employed as efficient cocatalytic materials to significantly promote the H 2 -production over Mn 0.5 Cd 0.5 S semiconductor. Particularly, the ternary 2MoO 2 /3Au/Mn 0.5 Cd 0.5 S nanocomposite containing 3 wt% Au NPs and 2 wt% MoO 2 exhibited the optimum H 2 -production activity (638.83 µmol h−1) under simulated sunlight conditions, more 3.73-, 1.74- and 1.35-fold enhancement relative to pristine Mn 0.5 Cd 0.5 S, binary 3Au/Mn 0.5 Cd 0.5 S and 2MoO 2 /Mn 0.5 Cd 0.5 S, respectively. Mechanistic characterizations demonstrate that the positive synergetic effects between Au NPs and MoO 2 can simultaneously boost the light absorption capacities, the separation efficiency of the interfacial charge carriers, and the thermodynamic performances of the hydrogen evolution reaction by strengthening the reduction ability of the photogenerated electrons and lowering the hydrogen evolution overpotential, which integratively resulted in the boosted photoactivity. [ABSTRACT FROM AUTHOR]

• Au decorated S-scheme Mn 0.5 Cd 0.5 S/WO 3 composite synthesized for H 2 -production. • Mechanism of charge transfer and separation in Au decorated S-scheme discussed. • High H 2 -production rate achieved over composite, 2.74 folds higher than Mn 0.5 Cd 0.5 S. Spontaneously solar-driven H 2 -production from water reduction provides a promising strategy to solve the aggravating energy and environment crises worldwide, but it is severely limited by the rapid charge-carrier recombination and the slashing redox potentials requirement. Here, a new ternary Mn 0.5 Cd 0.5 S/WO 3 /Au heterostructure photocatalyst has been designed by chemical deposition of Au nanoparticles (NPs) on Mn 0.5 Cd 0.5 S/WO 3 step-scheme (S-scheme) composite matrix to boost the photocatalytic activity through the multichannel-enhanced charge transfer/separation. By optimizing the constituent of the heterostructure photocatalyst, the prepared Mn 0.5 Cd 0.5 S/WO 3 /Au photocatalyst with 30 wt% of WO 3 and 4 wt% of Au exhibits the highest H 2 -evolution rate of 517.13 µmol h−1 under simulated solar light irradiation, more 2.74, 1.63 and 1.45 times higher than bare Mn 0.5 Cd 0.5 S and Mn 0.5 Cd 0.5 S loaded with WO 3 and Au alone, respectively. Mechanistic characterizations and control experiments have revealed that the S-scheme charge transfer in Mn 0.5 Cd 0.5 S/WO 3 heterojunction together with the "electron reservoir" resulting from the Au NPs contribute to the superior H 2 -generation activity over Mn 0.5 Cd 0.5 S/WO 3 /Au catalyst, which not only dramatically promotes the charge-carrier separation but also remains the strong redox ability of photoinduced electrons and holes in such photocatalytic system. [ABSTRACT FROM AUTHOR]

• A new ternary Mn 0.5 Cd 0.5 S/RGO-MoS 2 composite was successfully synthesized. • The synergetic effect between RGO and MoS 2 cocatalyst were discussed. • Mechanism of the enhanced photocatalytic activity was illuminated. A new solar-light-active ternary heterojunction photocatalyst, consisting of Mn 0.5 Cd 0.5 S nanoparticles grown on 2D reduced graphene oxide (RGO)-MoS 2 hybrid composite as a nonprecious and highly efficient cocatalyst has been successfully fabricated via a facile in-situ growth process. The optimized Mn 0.5 Cd 0.5 S/RGO-MoS 2 nanocomposite with 2 wt% RGO-MoS 2 cocatalyst displays the highest H 2 -evolution rate of 642.15 µmol h−1, which is about 3.75 times higher than bare Mn 0.5 Cd 0.5 S and far exceeding other composite photocatalysts, i.e., Mn 0.5 Cd 0.5 S/RGO, Mn 0.5 Cd 0.5 S/MoS 2 and noble Pt-modified Mn 0.5 Cd 0.5 S. It was revealed that the dramatically improved photoactivity of the ternary Mn 0.5 Cd 0.5 S/RGO-MoS 2 heterojunction photocatalyst was mainly originated from the positive cooperation between RGO and MoS 2 nanosheets. The RGO nanosheets with high conductivity could serve as an electron transport bridge to collect and transfer the photogenerated electrons effectively, while MoS 2 nanosheets with high electrocatalytic activity could act as an effective H 2 -evolution cocatalyst to facilitate the photoinduced electrons taking part in the hydrogen production reaction from water reduction, thus boosting the H 2 -evolution kinetics. More importantly, the RGO nanosheets could also lead to the downshift of the valence band (VB) of Mn 0.5 Cd 0.5 S, which was beneficial for the rapid oxidation of sacrificial agents and the interfacial charge transfer/separation, thereby helping to improve the photocatalytic performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Direct Z-scheme Mn 0.5 Cd 0.5 S/CoTiO 3 heterojunction was designed. • Mechanism for the enhanced photoactivity over Mn 0.5 Cd 0.5 S/CoTiO 3 heterojunction discussed. • High ammonia production rate achieved over heterojunction, 5.1-fold higher than Mn 0.5 Cd 0.5 S. The exploration and design of highly efficient and robust photocatalysts composed of earth-abundant materials for ambient photocatalytic N 2 fixation to ammonia remains a significant challenge. Here, we have fabricated a stable and highly efficient direct Z-scheme Mn 0.5 Cd 0.5 S/CoTiO 3 heterostructure for N 2 fixation by depositing Mn 0.5 Cd 0.5 S nanoparticles on CoTiO 3 surface. Under ambient conditions, the optimized Mn 0.5 Cd 0.5 S/CoTiO 3 heterojunction achieved a significant NH 3 production rate of 121.9 μmol g-1h−1 without cocatalyst modification, representing a 5.1- and 5.9-fold increase over pristine Mn 0.5 Cd 0.5 S and CoTiO 3 , respectively, and also exceeding most previously reported photocatalytic systems. The significant improvement in ammonia production primarily results from the Z-scheme charge transfer path between the Mn 0.5 Cd 0.5 S and CoTiO 3 components, which enables effective separation of photoinduced carriers while maintaining their robust redox capacity, thus dramatically boosting ammonia generation performance. This research may provide new insights for advancing other alternative Z-scheme photocatalytic systems with remarkable stability and exceptional efficiency in N 2 fixation. [ABSTRACT FROM AUTHOR]

Highlights • Inclined GeSn/Ge dual-nanowire heterostructure is grown on Ge(1 1 1) substrate by MBE. • Raman spectra of dual nanowires are numerically simulated. • Effective elastic strain relaxation in the dual-nanowire heterostructure is demonstrated. • Analytic fitting of Raman peak position is obtained to estimate the Sn content. Abstract In this paper, the Raman spectra of GeSn/Ge dual-nanowire heterostructure grown on Ge(1 1 1) substrate are systematically analyzed within the framework of anisotropic elasticity and lattice dynamical theory. Based on the experimental samples grown by molecular beam epitaxy, the partially covered dual nanowires standing along 〈1 1 0〉 direction are modeled and the heterostructure presents effective elastic strain relaxation due to the free surfaces. The simulations show that the Raman shift of GeSn nanowire is mainly affected by the Sn content while the influences of strain become less important with the increase of thickness ratio. For Ge nanowire, the peak of Raman spectrum merely moves with Sn content, but the spectrum possesses asymmetric broadening induced by the non-uniform strain distribution. The red-shift and intensity reduction of the total Raman spectrum of dual nanowires are observed when the Sn content increases. Moreover, an analytic fitting expression for Raman peak position is obtained based on the numerical results and is expected to serve as a reference to estimate the Sn content in GeSn/Ge dual-nanowire heterostructure. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spontaneous curvatures of Janus TMD nanoribbons are obtained by molecular statics simulations. • PGE of spontaneously curled Janus TMD photodetector with non-collinear electrodes is investigated by NEGF-DFT. • PGE photocurrent is enhanced by the spontaneous curling of Janus TMDs due to the reduction of symmetry. Enhancement of photogalvanic effect (PGE) in two-dimensional materials is of great importance for nanoscale self-powered optoelectronic devices. In this paper, we systematically investigate the generation of PGE photocurrent in six Janus transition metal dichalcogenides (MXY, M = Mo,W, X,Y = S,Se,Te) based on the quantum transport simulations. The proposed photodetectors along zigzag and armchair directions with non-collinear electrodes are built based on spontaneous curvatures of Janus TMDs. The spontaneous curling is induced by the relaxation of intrinsic strain in Janus TMDs and the curvatures are determined by molecular simulations. Vertically illuminated by linearly polarized light, PGE photocurrents can be observed in Janus TMDs with both curled and planar structure. The influences of polarization angle and photon energy on the photocurrents are quantitatively demonstrated. The photocurrents are largely amplified by more than 1 order of magnitude on average in the curled photodetector. This enhancement can be attributed to the device symmetry reduction from the C 3v to C s symmetry. We expect the results can help develop recipes for flexible two-dimensional optoelectronic devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ternary Mn 0.5 Cd 0.5 S/CB/CuS hierarchical multiheterojunction system was designed. • Synergetic effect between multifunctional CB and CuS dual cocatalysts discussed. • High H 2 -production rate achieved over composite, 4.79-fold higher than Mn 0.5 Cd 0.5 S. Developing exceptionally robust and cost-effective cocatalysts to suppress charge recombination and reduce the reaction energy barrier remains an enormous challenge for producing high-valued and storable hydrogen fuel from photocatalytic water splitting. Herein, novel Mn 0.5 Cd 0.5 S nanoparticles modified with multifunctional carbon black (CB) nanowires and CuS nanotubes as dual cocatalysts were fabricated via sonochemical loading, and subsequent in-situ deposition routes. In this ternary hierarchical architecture, both CB nanowires and CuS nanotubes can serve as normal electron cocatalysts to markedly promote the hydrogen generation performance by lowering the thermodynamic overpotential for hydrogen evolution. Moreover, due to the high electrical conductivity, the multifunctional CB material can also function as a bridge to effectively capture and transmit the photoexcited electrons from Mn 0.5 Cd 0.5 S to CuS with outstanding electrocatalytic hydrogen evolution activity, thus maximizing the carrier separation and H 2 -evolution reaction kinetics. Interestingly, the cooperative effects between CB and CuS dual cocatalysts are also helpful for improving the oxidation capacity of photoexcited holes by lowering the valence band position of Mn 0.5 Cd 0.5 S, which further accelerates the electron-hole separation. As a result, the constructed Mn 0.5 Cd 0.5 S/CB/CuS hierarchical multiheterojunction catalyst shows the superior hydrogen generation efficiency of 819.9 μmol h−1 and excellent stability under simulated solar light irradiation. [ABSTRACT FROM AUTHOR]

[Display omitted] • WS 2 decorated Mn 0.5 Cd 0.5 S/CuInS 2 p-n heterojunction synthesized for H 2 -production. • Multichannel charge-carrier transfer between Mn 0.5 Cd 0.5 S, CuInS 2 and WS 2 discussed. • High H 2 -production rate achieved over composite, 3.98-fold higher than Mn 0.5 Cd 0.5 S. Effective charge separation and sufficient light harvesting are crucial for photocatalytic water splitting into renewable and storable hydrogen energy. Employing WS 2 as cocatalyst and CuInS 2 as p-type semiconductor and photosensitizer, a novel WS 2 /Mn 0.5 Cd 0.5 S/CuInS 2 hierarchical tandem p-n heterostructure was constructed based on the energy band engineering theory. In this tandem p-n heterostructure, Mn 0.5 Cd 0.5 S nanoparticles adhere closely to CuInS 2 nanosheets to form a p-n junction along with the strong and monodirectional inner-built electric field, which can regulate the directional transfer/migration of photoinduced electrons-hole pairs and significantly boost the charge separation. Furthermore, the WS 2 cocatalyst employed in the ternary heterostructure further expedites the spatial charge separation and directional migration of photoexcited electrons, as well as simultaneously provides plentiful reaction active sites to decrease the activation barrier for hydrogen generation reaction. Benefiting from the synergetic cooperation of WS 2 cocatalyst and the p-n junction charge transfer channels, the smartly designed ternary WS 2 /Mn 0.5 Cd 0.5 S/CuInS 2 heterostructure displays the optimal photoactivity toward hydrogen production (681.7 μmol h−1), more 3.98-fold enhancement than individual Mn 0.5 Cd 0.5 S under simulated sunlight irradiation. This research provides a new avenue for constructing multi-hierarchical systems with remarkably boosted charge separation and light-harvesting abilities for high-efficiency solar energy conversion. [ABSTRACT FROM AUTHOR]

Abstract: Binary Al2O3/SiO2-coated rutile TiO2 composites were prepared by a liquid-phase deposition method starting from Na2SiO3·9H2O and NaAlO2. The chemical structure and morphology of binary Al2O3/SiO2 coating layers were investigated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, TG–DSC, Zeta potential, powder X-ray diffraction, and transmission electron microscopy techniques. Binary Al2O3/SiO2 coating layers both in amorphous phase were formed at TiO2 surfaces. The silica coating layers were anchored at TiO2 surfaces via Si–O–Ti bonds and the alumina coating layers were probably anchored at the SiO2-coated TiO2 surfaces via Al–O–Si bonds. The formation of continuous and dense binary Al2O3/SiO2 coating layers depended on the pH value of reaction solution and the alumina loading. The binary Al2O3/SiO2-coated TiO2 composites had a high dispersibility in water. The whiteness and brightness of the binary Al2O3/SiO2-coated TiO2 composites were higher than those of the naked rutile TiO2 and the SiO2-coated TiO2 samples. The relative light scattering index was found to depend on the composition of coating layers. [ABSTRACT FROM AUTHOR]

Abstract: Hollow silver spheres were successfully prepared by reducing AgNO3 with ascorbic acid and using negatively charged poly-(styrene-methyl acrylic acid) (PSA) spheres as templates in the presence of sodium polyacrylate as a stabilizer. Firstly, silver cations adsorbed on the surface of PSA spheres via electrostatic attraction between the carboxyl groups and silver cations were reduced in situ by ascorbic acid. The silver nanoparticles deposited on the surface of PSA spheres served as seeds for the further growth of silver shells. After that, extra amount of AgNO3 and ascorbic acid solutions were added to form PSA/Ag composites with thick silver shells. In order to obtain compact silver shells, the as-prepared PSA/Ag composites were heated at 150°C for 3h. Then hollow silver spheres were prepared by dissolving PSA templates with tetrahydrofuran. [Copyright &y& Elsevier]

Abstract: TiO2-coated sericite powders were prepared by the chemical deposition method starting from lamellar sericite and TiCl4 in the presence or absence of La3+ cations. After calcination at 900°C for 1h, the resultant TiO2 nanoparticles on the sericite surfaces existed in anatase phase. The light scattering indexes of the TiO2-coated lamellar sericite powders were dozens of times higher than that of the naked lamellar sericite powders. The presence of La3+ in the deposition solution was beneficial to the formation of the small-sized anatase TiO2 nanoparticles, resulting in the formation of the dense and uniform island-like TiO2 coating layers in a large range of the weight ratios of TiO2 to sericite from 5% to 20%. The TiO2-coated lamellar sericite powders prepared in the presence of La3+ had higher light scattering index than that prepared in the absence of La3+. XPS analysis shows that when La3+ cations were absent in the reaction solution, TiO2 coating layers anchored at the sericite surface via the Ti–O–Si and Ti–O–Al bonds. The presence of La3+ cations caused the formation of Si–O–La and Al–O–La bonds at the sericite surface and Ti–O–La bond at the surface of TiO2 coating layers. After coating TiO2 on the sericite surface, the yellowness of the TiO2-coated sericite powders obviously increased and the brightness slightly decreased. [Copyright &y& Elsevier]

• Equilibrium structures of Janus MoSSe quantum dots are theoretically investigated. • Two distinct curling types are observed in MD simulations. • The curling behavior is mainly governed by the size of QD. • The predominant driving force is the relaxation of intrinsic strain induced by atomic asymmetry in Janus structure. Motivated by the fascinating properties of both two-dimensional transition metal dichalcogenide quantum dots (TMD QDs) and Janus TMD monolayers, we theoretically explore the equilibrium structures of free-standing Janus MoSSe QDs in which atomic asymmetry of chalcogen is introduced. Two distinct types of spontaneous curling are observed by molecular dynamics simulations, and the curling behavior depends on the size of QD. The bowl-like (tube-like) curling occurs in relatively small (large) MoSSe QDs with different shapes (hexagon and triangle) and edge types (zigzag and armchair). The transition between these two curling types occurs at the sizes of around 10 nm and 13 nm for hexagonal and triangular shapes, respectively. By applying equivalent misfit strains into two adjacent sublayers, finite element analysis reproduces similar curling behavior. This confirms the relaxation of intrinsic strain in Janus structure acting as the predominant driving force of spontaneous curling. In addition, the curvatures of Janus TMD QDs increase from MoSSe to MoSeTe to MoSTe, indicating the positive correlation between the curling and misfit. [ABSTRACT FROM AUTHOR]