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Highlights: [•] We report a simple one-step hydrothermal synthesis on Ag2S nanoparticles. [•] The photoelectric properties of the Ag2S nanoparticles were studied. [•] A mechanism for the nucleation and growth of Ag2S NPs was proposed. [•] The concentration of surfactants impacts the grain diameter and the photoelectric properties. [Copyright &y& Elsevier]

Highlights: [•] The p-Cu2O/n-Cu2O homojunction film was prepared by electrodeposition. [•] We report the carrier kinetics of p-Cu2O/n-Cu2O homojunction film. [•] The interfacial electric field impacts the transfer direction of carrier. [•] The p-Cu2O/n-Cu2O homojunction film is used for sensing acetaldehyde. [ABSTRACT FROM AUTHOR]

Carbon-based Materials have been extensively researched for their prospect in the fields of environment and energy, especially for graphene oxide (GO). In this work, a novel sodium dodecyl sulfate (SDS)-assisted synthesis of BiOBr/Bi2WO6/GO ternary composite has been synthesized successfully by a handy hydrothermal method. Photoluminescence, Photocurrent, Electrochemical Impedance Spectroscopy, surface photovoltage and transient photovoltage measurements illustrate that construction of p-n BiOBr/Bi2WO6 heterojunction leads to the obviously enhancement of charge separation efficiency, and the photogenerated electrons trapped by GO can effectively inhibit the recombination process of photogenerated charge, resulting in the improvement of charge separation efficiency and the longer lifetime of photogenerated carriers for BiOBr/Bi2WO6/GO. The characterization of structure and morphology indicate that role of GO can also improve the visible light absorption range, and the SDS-assisted synthesis can reduce the size of particle in the composite and enhances the specific surface area of the composite by regulating the particle size and agglomeration. Under optimal conditions, BiOBr/Bi2WO6/GO (SDS) has the outstanding photocatalytic degradation performance and the degradation rate constants for oxytetracycline, tetracycline hydrochloride, methylene blue and rhodamine are 0.056, 0.057, 0.103 and 0.414 min−1, respectively. Notably, the degradation rate constants obtained by BiOBr/Bi2WO6/GO (SDS) are more ten times higher than that of pure BiOBr and Bi2WO6. The possible mechanism of photocatalytic degradation was suggested for BiOBr/Bi2WO6/GO based on the dynamic properties of photogenerated charge and reactive oxidation species results. Surprisingly, the recyclability of the BiOBr/Bi2WO6/GO (SDS) composite obtained from the cyclic experiments has laid a foundation for the study of efficient and stable photocatalysts. [ABSTRACT FROM AUTHOR]

Abstract: TiO2(B) was prepared by a facile green solvothermal method and further characterized by the powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), raman spectroscopy and nitrogen sorption analysis, and it has been found that the as-synthesized sample possesses a unique crystallites/nanopores structure and has a very large surface area (484m2 g−1). Surprisingly, it exhibits the very high photocatalytic activity and good stability for the decomposition of methyl orange (MO) compared to that of P25. [ABSTRACT FROM AUTHOR]

Abstract: A large aligned nanorod array of α-Fe2O3 grown on FTO substrate was prepared via a simple hydrothermal synthesis method. The photoelectric property of the array was studied by surface photovoltage technique. Based on the photovoltage responses on spectrum, we discussed the transfer characteristics of the photogenerated charge at the surface of the nanorods and the interface between the nanorods and the FTO substrate. The contributions of surface states and built-in electric field were discriminated. Moreover, the quantum size effect on the photovoltage spectra could be observed only when the array was illuminated from the free surface of the nanorods. [Copyright &y& Elsevier]

Constructing π‐conjugated polymer structures through covalent bonds dominates the design of organic framework photocatalysts, which significantly depends on the selection of multiple donor‐acceptor building blocks to narrow the optical gap and increase the lifetimes of charge carriers. In this work, self‐bipolarized organic frameworks of single aromatic units are demonstrated as novel broad‐spectrum‐responsive photocatalysts for H2O2 production. The preparation of such photocatalysts is only to fix the aromatic units (such as 1,3,5‐triphenylbenzene) with alkane linkers in 3D space. Self‐bipolarized aromatic units can drive the H2O2 production from H2O and O2 under natural sunlight, wide pH ranges (3.0‐10.0) and natural water sources. Moreover, it can be extended to catalyze the oxidative coupling of amines. Experimental and theoretical investigation demonstrate that such a strategy obeys the mechanism of through‐space π‐conjugation, where the closely face‐to‐face overlapped aromatic rings permit the electron and energy transfer through the large‐area delocalization of the electron cloud under visible light irradiation. This work introduces a novel design concept for the development of organic photocatalysts, which will break the restriction of conventional through‐band π‐conjugation structure and will open a new way in the synthesis of organic photocatalysts. [ABSTRACT FROM AUTHOR]

Abstract: The photovoltaic properties of nanoporous TiO2 film treated with Al3+ ions have been investigated by the spectral and transient photovoltage (PV) technique. The performances of the dye-sensitized solar cells (DSSCs) with different amounts of aluminum oxide were compared. The results showed that with increased amount of aluminum oxide, the spectral PV responses blue shift (with the exception of the 0.1wt%) and the time of the transient PV maximum increase. The performances of the corresponding cells were improved. These results indicated the dependence of the DSSCs performances on the charge dynamics in the corresponding nanoporous TiO2 film. [Copyright &y& Elsevier]

Supercapacitors often deliver a significantly high-power density with a long cycling life but low energy density. An exceedingly promising approach is to construct asymmetric supercapacitors (ASCs) reconciling the compromise between power density and energy density. However, ASCs combining transition metal oxides (TMOs) and activated carbon (AC) struggle to improve energy density due to a vast difference in their specific capacitance. To cross this hurdle, we first proposed a new strategy to construct the ASCs with α-MoO3 as the anode and conductive polymer polypyrrole (PPy) as the cathode. The remarkable features of α-MoO3, including its layered structure and ultra-high specific capacitance, along with the stability and fast charge–discharge ability of PPy, have contributed significantly to the augmentation of power density and energy density in ASCs. Taking advantage of these bright features, the operation voltage for α-MoO3//PPy is effectively expanded to 2.0 V, exhibiting a high energy density of 25.9 W h kg−1 at 1538 W kg−1. Furthermore, the energy density presented a remarkable recovery rate, reaching 91.04% of its initial state after undergoing full rate tests. These conclusions reveal that the construction of α-MoO3//PPy can effectively enhance the energy density and power density of supercapacitors. [ABSTRACT FROM AUTHOR]

The sustainable production of hydrogen utilizing solar energy is a pivotal strategy for reducing reliance on fossil fuels. ZnIn2S4 (ZIS), as a typical metal sulfide semiconductor, has received extensive attention in photocatalysis. Although the introduction of sulfur (S) vacancies in ZIS to enhance photocatalytic hydrogen production by creating defect energy levels has been explored, detailed studies on the control and modulation of S‐vacancies in ZIS are sparce. This study demonstrates that while moderate levels of S‐vacancies can enhance hydrogen evolution, excessive vacancies may hinder the process, underscoring the importance of S‐vacancy modulation. Guided by theoretical calculations, We have designed and synthesized ZIS with modulated S‐vacancies to realize favorable hydrogen adsorption‐free energy and integrated in a Schottky‐heterojunction with MXene co‐catalysts for enhanced hydrogen evolution. The optimized hydrogen evolution performance of ZnIn2S4/MXene (ZMX) reaches 14.82 mmol g−1 h−1 under visible light irradiation, surpassing many reported ZnIn2S4‐based photocatalysts. The enhanced performance is ascribed to widened light absorption and enhanced carrier transportation realized by S‐vacancy modulation and the co‐catalytic effect. Femtosecond ultrafast absorption (fs‐TA) spectra and other in‐situ/ex‐situ characterizations further prove an efficient separation and transfer in an as‐prepared ZMX catalyst. These findings open up new perspectives for designing catalysts with vacancy modulation. [ABSTRACT FROM AUTHOR]

The development of photoelectrochemical (PEC) water splitting is hindered by the slow kinetics of four-electron processes for the oxygen evolution reaction (OER) and severe charge recombination. Amorphous carbon was chosen as a carrier for the active sites due to its exceptional conductivity and strong loading capacity. In addition, this enhanced performance was attributed to the loading of oxides of cobalt. Here, amorphous carbon-covered cobalt oxides chosen as a co-catalyst loaded on α-Fe2O3 (noted as CoOx@C/Ti-Fe2O3) have been synthesized, and they show a high current density (2.86 mA cm−2 under 1.23 V vs. RHE), and a low onset potential (0.611 V vs. RHE). Experimental analysis demonstrates that the charge transfer and separation leading to accelerated OER dynamics and improved PEC performance are enhanced by CoOx@C effectively. This study provides new ideas for designing high-performance photoelectrochemical electrodes based on amorphous carbon co-catalysts. [ABSTRACT FROM AUTHOR]

The loading of PDS improves the separation of photogenerated carriers, suppresses the bulk and surface recombination (including surface recombination of the back electron(BER)), and enhances the water oxidation kinetics, synthetically improves the PEC water oxidation performance [Display omitted] The kinetic competition between water oxidation/electron extraction processes and recombination behaviors is a key consideration in the development of efficient photoanodes for solar-driven water splitting. Investigating the photogenerated charge behaviors could guide the construction of high-efficiency photoanodes. In this study, the charge carrier kinetics involved in photoelectrochemical water oxidation of PDS/Ti-Fe 2 O 3 were analyzed using surface photovoltage (SPV), transient photovoltage (TPV), short-pulse transient photocurrent (TPC) and photoelectrochemical impedance spectra (PEIS). The TPC results indicate the interfacial electric field introduced by the PDS loading increases the electron extraction and suppresses the bulk recombination, enhancing the spatial separation of photogenerated charges, which is consistent with the SPV and TPV results. Besides, the surface recombination of the back electron (BER) is also attenuated, which enhances the long-lived holes at the surface of PDS/Ti-Fe 2 O 3 photoanode. Similarly, as obtained by PEIS fitting, the loading of PDS accelerates holes transfer at the photoanode/electrolyte interface, and increases the utilization of long-lived holes. In other word, the recombination behaviors of photogenerated charges are restrained both in the bulk and surface of the photoanode after the deposition of PDS, leading to enhanced PEC performance. These findings highlight the importance of understanding charge carrier dynamics in the design of high-efficient photoanodes. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting holds great promise as a sustainable and cost‐effectiveness alternative for the production of hydrogen. Nevertheless, the practical implementation of this strategy is hindered by suboptimal visible light utilization and sluggish charge carrier dynamics, leading to low yield. MXene is a promising cocatalyst due to its high conductivity, abundance of active sites, tunable terminal functional groups, and great specific surface area. Homo‐interface has perfect lattice matching and uniform composition, which are more conducive to photogenerated carriers' separation and migration. In this study, a novel ternary heterogeneous photocatalyst, a‐TiO2/H‐TiO2/Ti3C2 MXene (MXTi), is presented using an electrostatic self‐assembly method. Compared to commercial P25, pristine anatase, and rutile TiO2, as‐prepared MXTi exhibit exceptional photocatalytic hydrogen evolution performance, achieving a rate of 0.387 mmol h−1. The significant improvement is attributable to the synergistic effect of homo‐interface engineering and Ti3C2 MXene, which leads to widened light absorption and efficient carrier transportation. The findings highlight the potential of interface engineering and MXene cocatalyst loading as a proactive approach to enhance the performance of photocatalytic water splitting, paving the way for more sustainable and efficient hydrogen production. [ABSTRACT FROM AUTHOR]

An effective scheme and technical means for understanding the mechanism of interfacial charge transfer. [Display omitted] • The Z-scheme Ti-ZFO/In 2 O 3 photoelectrode was successfully constructed. • Ti-ZFO/In 2 O 3 reaches 2.2 mA/cm2 at 1.23 V vs. RHE, which is 7 times that of pure Ti-ZFO. • The Z-scheme Ti-ZFO/In 2 O 3 could promote the separation and transfer of charges effectively. • This work provides an effective method and technical means to understanding the Z-scheme mechanism. Ti-ZnFe 2 O 4 photoanode has attracted extensive attention in photoelectrochemical (PEC) water oxidation due to its narrow band gap and good photostability. However, its low efficiency limits its development. Herein, we designed and constructed direct Z-scheme Ti-ZnFe 2 O 4 /In 2 O 3 (Ti-ZFO/In 2 O 3) photoanode. Under the interface electric field, photogenerated holes with stronger oxidation capacity on In 2 O 3 are retained to participate in the water oxidation reaction, and the photocurrent density of Ti-ZFO/In 2 O 3 is much higher than that of pure Ti-ZFO, reaching 2.2 mA/cm2 at 1.23 V vs. RHE. Kelvin Probe, steady-state photovoltage spectroscopy (SPV), transient photovoltage spectroscopy (TPV) and in-situ double beam strategy were used to demonstrate the Z-scheme charge transfer mechanism of Ti-ZFO/In 2 O 3 photoanode. Our work provides an effective scheme and technical means for further understanding the mechanism of interfacial charge transfer. [ABSTRACT FROM AUTHOR]

The slow kinetics of water oxidation has become a challenge for photoelectrochemical hydrogen production. Here, a novel organic-inorganic integrated photoanode system was constructed by using MIL-53(Fe) formed during the in-situ etching process as a cocatalyst to modify Ti–Fe 2 O 3. The photocurrent density of Ti–Fe 2 O 3 /MIL-53(Fe) reaches 2.5 mA/cm2, 10 times that of bare Ti–Fe 2 O 3 at 1.23 V vs. RHE, and the water oxidation photocurrent onset potential shifts 105 mV negatively. Ti–Fe 2 O 3 /MIL-53(Fe) reaches 52% at 390 nm for IPCE. The excellent photoelectrochemical performance is due to iron oxide clusters boost charge separation and transfer, in-situ etching exposes more reactive sites, and the tight connection reduces interfacial resistance, which greatly accelerates the surface kinetics of Ti–Fe 2 O 3. The in-depth understanding is provided for in-situ modification of photoanodes by metal organic frameworks in this work. The in-depth understanding is provided for in-situ modification of photoanodes by metal organic frameworks in this work. [Display omitted] • Ti–Fe 2 O 3 /MIL-53(Fe) photoelectrode was successfully constructed. • Ti–Fe 2 O 3 /MIL-53(Fe) reaches 2.5 mA/cm2 at 1.23 V vs. RHE, which is 10 times that of bare Ti–Fe 2 O 3. • MIL-53(Fe) greatly improves the water oxidation reaction kinetics of Ti–Fe 2 O 3. • This work provides a new insight into charge transfer in inorganic-organic hybrid systems. [ABSTRACT FROM AUTHOR]

Aurivillius‐type compounds ((Bi2O2)2+(An–1BnO3n+1)2−) with alternately stacked layers of bismuth oxide (Bi2O2)2+ and perovskite (An−1BnO3n+1)2− are promising photocatalysts for overall water splitting due to their suitable band structures and adjustable layered characteristics. However, the self‐reduction of Bi3+ at the top (Bi2O2)2+ layers induced by photogenerated electrons during photocatalytic processes causes inactivation of the compounds as photocatalysts. Here, using Bi3TiNbO9 as a model photocatalyst, its surface termination is modulated by acid etching, which well suppresses the self‐corrosion phenomenon. A combination of comprehensive experimental investigations together with theoretical calculations reveals the transition of the material surface from the self‐reduction‐sensitive (Bi2O2)2+ layer to the robust (BiTiNbO7)2− perovskite layer, enabling effective electron transfer through surface trapping and effective hole transfer through surface electric field, and also efficient transfer of the electrons to the cocatalyst for greatly enhanced photocatalytic overall water splitting. Moreover, this facile modification strategy can be readily extended to other Aurivillius compounds (e.g., SrBi2Nb2O9, Bi4Ti3O12, and SrBi4Ti4O15) and therefore justify its usefulness in rationally tailoring surface structures of layered photocatalysts for high photocatalytic overall water‐splitting activity and stability. [ABSTRACT FROM AUTHOR]

An amorphous tantalum oxyhydroxide TaO x (OH) y homojunction is constructed by anchoring TaO x (OH) y (2x + y = 5) nanoparticles (NPs, size: 4–10 nm) in situ on the surface of TaO x (OH) y sphere (SP). The formation of amorphous homojunction (TaO x (OH) y NPs/SP) is demonstrated by detailed characterizations of transmission electron microscopy, thermogravimetric analysis/mass spectrometer, Fourier transfer infrared spectra and X-ray photoelectron spectroscopy. In the absence of cocatalyst, the constructed amorphous homojunction exhibits a photocatalytic H 2 evolution rate of 311.1 μmol/g/h, about 5, 40 and 1000 times higher than that of 66.8 μmol/g/h for bare TaO x (OH) y SP, 7.6 μmol/g/h for commercial Ta 2 O 5 , and 0.3 μmol/g/h for the most widely used photocatalyst P25 (mixed-phase titania). The splendid performance is attributed to the special amorphous homojunction that produces a type-II band alignment and robust separation of photo-excited charge carriers, as uncovered by ultraviolet photoelectron, photoluminescence spectroscopy, and surface/transient photovoltage data. Our findings for amorphous homojunction may provide a new strategy of developing effective noncrystalline photocatalysts. [ABSTRACT FROM AUTHOR]

The polyporous SnO 2 -ZnO composites were synthesized by a water-bath method. The 3D center-hollow architecture and polyporous surface were also confirmed by field-emission scanning electron microscope (FE-SEM) and the Brunauer-Emmett-Teller (BET) specific surface area. Meanwhile, structural properties of SnO 2 -ZnO have been investigated by trans-mission electron microscopy (TEM) in 1 mol% SnO 2 -ZnO. The results of photoelectric gas-sensing demonstrated that the 1 mol% SnO 2 -ZnO gas-sensor exhibits not only an excellent response to formaldehyde (HCHO) but also superior sensitivity to low HCHO concentration. The response of 1 mol% SnO 2 -ZnO for the 1 ppm HCHO has reached 30% at room temperature (25 °C), and a detection limit of 0.1 ppm HCHO was achieved. The behavior of photogenerated charge is discussed in detail by means of the surface photovotage (SPV) and the transient photovoltage (TPV) techniques. It was found that the as-prepared 1 mol% SnO 2 -ZnO composites showed excellent separation and transfer efficiency of photogenerated charges carriers. What's more, the TPV spectrum analysis provides convincing evidence that the addition of excess SnO 2 is unfavorable to the transfer of electrons so as to reduce the sensitivity of SnO 2 -ZnO for target gas. This result offers a new window to explain the effect of SnO 2 concentration on the gas sensing characteristics, and provide more information on the fabricating composite materials for gas sensors. [ABSTRACT FROM AUTHOR]

Improving the water-splitting performance of hematite (α-Fe 2 O 3) is still hindered due to its severe charge recombination and poor water oxidation kinetics. Herein, borate-treated Ti–Fe 2 O 3 combined with a Fe x Ni 1-x OOH cocatalyst (Fe x Ni 1-x OOH/B/Ti–Fe 2 O 3) greatly improved the performance of Ti–Fe 2 O 3 , and reached a notable photocurrent density of 3.39 mA/cm2 at 1.23 V vs. RHE. Transient surface photovoltage spectroscopy (TPV) directly reveals that [B(OH) 4 ]− as a Lewis base can selectively passivate acceptor surface states on Ti–Fe 2 O 3 photoanode surface, efficiently enhancing the charge separation efficiency. Moreover, the Fe x Ni 1-x OOH thin layer is devoted to further facilitate holes injection into the electrolyte, accelerating the water oxidation kinetics of Ti–Fe 2 O 3 photoanode. The synergetic integration of acceptor surface states passivation and Fe x Ni 1-x OOH cocatalyst provides a novel strategy for the construction of efficient photoanodes by surface engineering. [Display omitted] • [B(OH) 4 ]− as a Lewis base can selectively passivate acceptor surface states. • The Fe x Ni 1-x OOH thin layer can further improve water oxidation kinetics. • Fe x Ni 1-x OOH/B/Ti–Fe 2 O 3 could achieve 3.39 mA/cm2 at 1.23 V vs. RHE. • Fe x Ni 1-x OOH/B/Ti–Fe 2 O 3 exhibits the outstanding PEC performance. [ABSTRACT FROM AUTHOR]

Constructing a high-efficiency and low-cost cocatalyst on g-C3N4 is of great significance for realizing efficient photocatalytic hydrogen production. However, balancing the active center and mass transport is still a great challenge in the design of a cocatalyst. Herein, a Ni@Ni2P cocatalyst with a core–shell structure was rationally fabricated on g-C3N4 such that photogenerated electrons could transfer to Ni2P through Ni directionally and orderly, as their amount can strongly influence photocatalytic H2 evolution performance. The optimal H2 evolution rate of 50P-Ni reaches 2.9 mmol h−1 g−1, which is about 3.5-fold and 137-fold higher than that of g-C3N4 and Ni/g-C3N4, respectively. Systematic investigations reveal that the Ni@Ni2P cocatalyst with a unique core–shell structure not only endows Ni metal with stability from corrosion but also prolongs the recombination time of photoinduced electrons and holes, which results in better separation efficiency. This work provides useful inspiration for rationally designing a robust and efficient core–shell cocatalyst for photocatalytic H2 evolution. [ABSTRACT FROM AUTHOR]

Photogenerated carrier behavior at a CO2/Cs2AgBiBr6 quantum dot (QD) interface is investigated. In situ photovoltage spectra reveal electron transfer from the Cs2AgBiBr6 QDs to CO2. Moreover, this carrier transfer prefers Bi3+ sites (over Ca+ and Ag+ sites) due to them exhibiting the lowest adsorption energy (Eads = −0.125 eV) and CO2–Bi3+ interactions being more stable. [ABSTRACT FROM AUTHOR]

Interface modification is an important means to enhance the photovoltaic performance of quantum dot sensitized solar cells (QDSCs). The TiO2/CdS/CdSe solar cells are sensitized with CdS QDs and CdSe QDs, which inevitably introduces a new interface to form a recombination center. Therefore, it is necessary to coat a passivation layer in order to effectively inhibit charge recombination at the CdS/CdSe interface. In this work, CuInS2 (CIS) has been introduced into the CdS/CdSe QD system as an inner passivation layer and the CdS/CIS/CdSe photoanode structure has been fabricated in an environmentally friendly manner. The extracted charge amount (Q) is used to express the charge separation efficiency, indicating that we have obtained outstanding charge extraction efficiency in CIS based CdS/CdSe QDSCs. As a result, the photocurrent density of the TiO2/CdS/CIS/CdSe photoanode significantly has increased from 19.01 mA cm−2 to 22.74 mA cm−2 (TiO2/CdS/CdSe photoanode), which demonstrates a higher photoconversion efficiency of 4.52% in comparison with that of TiO2/CdS/CdSe photoanode. [ABSTRACT FROM AUTHOR]

The appropriate band energy of H 2 TCPP matched with Ti-Fe 2 O 3 and CoPi assists more photogenerated holes to migrate to CoPi for PEC water oxidation reaction. [Display omitted] Coupling porphyrins with semiconductors is demonstrated as one of effective means to facilitate the separation of photogenerated charge in dye-sensitized solar cells as well as photocatalytic hydrogen production. However, there are limited reports about exploring the effect of porphyrin on the behavior of photogenerated charges and photoelectrochemical (PEC) water oxidation performance. Herein, we have built a hybrid photoanode containing Ti doped α-Fe 2 O 3 (Ti-Fe 2 O 3), 5,10,15,20-tetrakis (4-carboxyl phenyl) porphyrin (H 2 TCPP) and cobalt phosphate (CoPi) cocatalyst. Because of the appropriate band alignment of Ti-Fe 2 O 3 , H 2 TCPP and CoPi, the photogenerated holes are transferred directionally from Ti-Fe 2 O 3 to CoPi across H 2 TCPP, which boosts the separation efficiency of CoPi/H 2 TCPP/Ti-Fe 2 O 3 in turn. Meanwhile, CoPi/H 2 TCPP/Ti-Fe 2 O 3 possesses higher injection efficiency as well. Under the double guarantee of high separation efficiency and injection efficiency, CoPi/H 2 TCPP/Ti-Fe 2 O 3 yields an impressive photocurrent density of 1.84 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (RHE), which is much higher than that of CoPi/Ti-Fe 2 O 3. This structure design describes an appealing maneuver to facilitate the directed migration of photogenerated charges and then enhance the PEC water oxidation performance. [ABSTRACT FROM AUTHOR]

Inverted perovskite solar cells (PSCs) have been extensively studied by reason of their negligible hysteresis effect, easy fabrication, flexible PSCs and good stability. The certified photoelectric conversion efficiency (PCE) achieved 23.5% owing to the formed lead−sulfur (Pb−S) bonds through the surface sulfidation process of perovskite film, which gradually approaches the performance of traditional upright structure PSCs and indicates their industrial application potential. However, the fabricated devices are severely affected by moisture, high temperature and ultraviolet light due to the application of organic materials. Depending on nitrogen, cost of protection may increase, especially for the industrial production in the future. In addition, the inverted PSCs are found with a series of issues compared with the traditional upright PSCs, such as nonradiative recombination of carriers, inferior stability and costly charge transport materials. Thus, the development of inverted PSCs is systematically reviewed in this paper. The design and fabrication of charge transport materials and perovskite materials, enhancement strategies (e.g., interface modification and doping) and the development of all−inorganic inverted devices are discussed to present the indicator for development of efficient and stable inverted PSCs. [ABSTRACT FROM AUTHOR]

As the third generation of new thin-film solar cells, perovskite solar cells (PSCs) have attracted much attention for their excellent photovoltaic performance. Today, PSCs have reported the highest photovoltaic conversion efficiency (PCE) of 25.5%, which is an encouraging value, very close to the highest PCE of the most widely used silicon-based solar cells. However, scholars have found that PSCs have problems of being easily decomposed under ultraviolet (UV) light, poor stability, energy level mismatch and severe hysteresis, which greatly limit their industrialization. As unique materials, quantum dots (QDs) have many excellent properties and have been widely used in PSCs to address the issues mentioned above. In this article, we describe the application of various QDs as additives in different layers of PSCs, as luminescent down-shifting materials, and directly as electron transport layers (ETL), light-absorbing layers and hole transport layers (HTL). The addition of QDs optimizes the energy level arrangement within the device, expands the range of light utilization, passivates defects on the surface of the perovskite film and promotes electron and hole transport, resulting in significant improvements in both PCE and stability. We summarize in detail the role of QDs in PSCs, analyze the perspective and associated issues of QDs in PSCs, and finally offer our insights into the future direction of development. [ABSTRACT FROM AUTHOR]

ZnO nanofibers, nanoplates, nanoflowers have been successfully synthesized by simple electrospinning and hydrothermal routes, respectively. The characterization of three samples was studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV–vis diffuse reflectance spectrum (UV–vis DRS). The effects of ZnO nanostructure morphology on the gas-sensing property of HCHO have been investigated. The gas sensor based on ZnO nanofibers showed a high sensitivity, reversible response and good selectivity towards HCHO under the irradiation of 365 nm UV-light at room temperature. These desirable sensing features can be attributed to the special network structure with larger specific surface areas and its one-dimensional arrangement of ZnO nanocrystallites with a larger proportion of the depletion layer, which results in more obvious adjustment of the depletion layer width. The results confirm that ZnO nanofibers obtained by the electrospinning are attractive chemical sensing materials. [ABSTRACT FROM AUTHOR]

A series of nano-spindly BiVO 4 and Ag-BiVO 4 were synthesized by a simple solvothermal method. X-ray photoelectron spectroscopy (XPS) and high resolution electron microscopy (HRTEM) analysis indicated that the chemical state of the Ag particles was metallic Ag. Their photocatalytic activities were evaluated by the decolorization of rhodamine B (RhB) under visible light irradiation ( λ > 420 nm). The research of photoinduced charge properties of samples studied by surface photovoltage spectroscopy (SPS) and electric field-induced surface photovoltage spectroscopy (FISPS) measurement system and the results indicated that the existence of Ag attained the enhancement of photoinduced charge carriers’ separation. This was thought to be responsible for the higher efficient photocatalytic activity of Ag-BiVO 4 in the degradation of RhB. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Z-scheme NH 2 -MIL-125(Ti)/Ti-Fe 2 O 3 photoanode is designed and constructed. • NH 2 -MIL-125(Ti)/Ti-Fe 2 O 3 shows excellent PEC performance and stability. • The Z-scheme pathway is identified by surface photovoltage, ESR and fs-TAS. • Efficient separation of interface and surface carriers is simultaneously realized. The construction of Z-scheme charge transfer pathways simulating natural photosynthesis is considered a promising method for improving reaction driving forces. Here, we modified the surface of titanium doped Fe 2 O 3 (Ti-Fe 2 O 3) nanorods with NH 2 -MIL-125(Ti) (Ti-MOFs) and a promising organic-inorganic hybrid Z-scheme NH 2 -MIL-125(Ti)/Ti-Fe 2 O 3 was successfully prepared. At 1.23 V vs. RHE, the photocurrent density of the composite photoanode reaches 2.67 mA/cm2, which is 5 times higher than that of Ti-Fe 2 O 3. The results of surface photovoltage, ESR and fs-TAS indicate that this improvement is mainly due to the effective Z-scheme charge transfer mechanism providing a strong driving force for charge separation and transport, greatly suppressing carrier recombination and allowing carriers with strong oxidation ability to participate in water oxidation. Meanwhile, NH 2 -MIL-125(Ti) can enhance light absorption and reduce the surface defect state of Ti-Fe 2 O 3. This study not only provides a feasible approach for the photoanode water splitting of traditional inorganic semiconductor/MOF based heterostructures, but also provides rich and effective means for revealing Z-scheme charge transfer mechanism in depth. [ABSTRACT FROM AUTHOR]

In this paper, MOF-In 2 S 3 were modified by ZnFe-layered dioxides (LDO) with strong stability to obtain high catalytic performance composite. The successful preparation of ZnFe-LDO/MOF-In 2 S 3 not only retains the advantages of large specific surface area of MOF-In 2 S 3 and the stability of ZnFe-LDO, but also improves its charge separation efficiency and the light absorption region through the construction of heterojunctions. As expected, the experimental results show that ZnFe-LDO/MOF-In 2 S 3 has superior photo-electrocatalytic properties. The photocatalytic degradation efficiency of ZnFe-LDO/MOF-In 2 S 3 for TCH and OTC reach 92.92% and 80%, respectively, within 25 min. And the corresponding degradation rate constants are up to 1.41332 and 0.45451 L·mg−1·min−1, respectively, which are accord with the pseudo-second-order kinetic constants. The intermediate of 0.6LDO/M-I degradation of TCH was proposed by liquid mass spectrometry (LC-MS). Notably, a special transient surface photovoltage (TPV) technique was used for discussing the charge transfer kinetics and the lifetime of photogenerated carriers. Based on Mott-Schottky (M-S), Ultraviolet-visible absorption spectrum (UV), X-ray Photoelectron Spectroscopy (XPS) results, electron paramagnetic resonance (EPR) results, and active substance capture experiment results, a Z-scheme heterojunction system was proposed. The above research work proposed a new approach to enhance the stability of catalytic materials by using the aid of layered dioxides. In addition, the characterization of surface photovoltage provides a new way to study charge transfer. In this paper, a novel ZnFe-LDO/MOF-In 2 S 3 composite material has been successfully prepared, and its general morphology is mainly composed of MOF-In 2 S 3 nanoparticles coated with ZnFe-LDO material. After characterization and conclusion analysis, the catalyst material conforms to Z-scheme heterostructure and has excellent charge transfer rate and catalytic efficiency. [Display omitted] • ZnFe-LDO/MOF-In 2 S 3 Z-scheme composite was prepared successfully for the first time. • ZnFe-LDO/MOF-In 2 S 3 has excellent carrier separation efficiency, wide light absorption range and high redox capacity. • The photocatalytic degradation efficiency of 0.6LDO/M-I for TCH and OTC were 92.92% and 80%, respectively. • The corresponding degradation rate constants of 0.6LDO/M-I accord with the pseudo-second-order kinetic constants. [ABSTRACT FROM AUTHOR]

Cobalt-based metal-organic frameworks (Co-MOFs) are considered excellent cocatalysts for improving the photoelectrochemical performance of photoanodes. Considering the boundedness of monometallic MOFs, introducing a second metal is an efficient method to enhance the activity and stability of Co-MOFs. In this work, Cu doped Co-MOFs was successfully decorated on Ti–Fe 2 O 3 to prepare Ti–Fe 2 O 3 /CoCu-MOF. The photocurrent density of composite photoanode at 1.23 V vs. RHE reaches 2.06 mA/cm2, 5.5 times higher than that of Ti–Fe 2 O 3 , and the onset potential shifts 170 mV negatively. The results showed that CoCu-MOFs thin layer not only provided abundant active sites, but also effectively passivated the acceptor surface states of Ti–Fe 2 O 3 , thus inhibiting surface charge recombination. In addition, the introduction of Cu2+ can induce the generation of higher valence Co species, which significantly promotes the transfer of holes from Ti–Fe 2 O 3 to the electrolyte. Our work demonstrates a new and promising photoelectrochemical cocatalyst, and provides a convenient method for the construction of other bimetallic MOFs materials. This work has gained a deeper understanding of the impact of CoCu-MOFs on photoanode water oxidation, and provided new strategies for the application of other bimetallic MOFs in the field of energy conversion. [Display omitted] [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) are currently attracting a great deal of attention for their excellent photovoltaic properties, with a maximum photoelectric conversion efficiency (PCE) of 25.5%, comparable to that of silicon-based solar cells. However, PSCs suffer from energy level mismatch, a large number of defects in perovskite films, and easy decomposition under ultraviolet (UV) light, which greatly limit the industrial application of PSCs. Currently, quantum dot (QD) materials are widely used in PSCs due to their properties, such as quantum size effect and multi-exciton effect. In this review, we detail the application of QDs as an interfacial layer to PSCs to optimize the energy level alignment between two adjacent layers, facilitate charge and hole transport, and also effectively assist in the crystallization of perovskite films and passivate defects on the film surface. [ABSTRACT FROM AUTHOR]

Developing the technology for high yielding photocatalytic hydrogen evolution reactions is an important challenge. Development and optimization of photocatalytic junctions is a likely route for achieving this if heterojunctions with suitable band alignments can be achieved in sufficiently high‐density form. Here, a novel anatase‐TiO2/H‐rutile‐TiO2 heterophase homojunction system with near optimum energy band alignment is reported. The resulting as‐prepared catalyst exhibits an excellent photocatalytic hydrogen evolution rate of 29.63 mmol g–1 h–1 under UV–vis light irradiation and an outstanding apparent quantum efficiency of 45.6% at 365 nm. The significant improvement is ascribed to near perfect lattice matching in combination with the rapid separation and transfer of photogenerated carriers in anatase‐TiO2/H‐rutile‐TiO2 heterophase homojunctions. In situ X‐ray photoelectron spectroscopy, electron spin resonance spin‐trapping tests, femtosecond transient absorption spectroscopy, steady‐state surface photovoltage spectroscopy, and transient‐state surface photovoltage with additional ex situ characterizations and theoretical calculations show that the mechanism is enhanced transfer of photogenerated carriers in the anatase‐TiO2/H‐rutile‐TiO2 catalyst. This work provides a pathway for enhancing photocatalytic performance through optimization of heterojunctions. [ABSTRACT FROM AUTHOR]

One of the key objectives for the hematite photoanode is to accelerate the kinetics of oxidative water splitting and inhibit the recombination of electron and hole. Here, we report a titanium boride (TiB2)-modified hematite (α-Fe2O3) photoanode produced by spin coating and subsequent calcination; a surface oxidized layer is formed during this process. The photocurrent density of the surface-oxidized TiB2 on α-Fe2O3 (α-Fe2O3/SO-TiB2) photoanode [at 1.23 V versus reversible hydrogen electrode (vs. RHE), 2.0 mA cm−2] is observably increased compared to α-Fe2O3 (at 1.23 vs. RHE, 0.57 mA cm−2). In addition, the SO-TiB2-decorated heterogeneous junction hematite (HJ-Fe2O3/SO-TiB2) has greater photocurrent activity (at 1.23 vs. RHE, 2.5 mA cm−2). This improvement of the photoelectrochemical (PEC) property is due to the formation of a surface oxide layer, which regulates the direction of the interface electric field, improving improves the separation and injection efficiency of photogenerated charges, as proved by photophysical characterization and PEC measurements. Thereby, the water oxidation kinetics for the α-Fe2O3-based photoanode are significantly accelerated. [ABSTRACT FROM AUTHOR]

[Display omitted] Covalent triazine-based frameworks (CTFs) have been emerged as a promising organic material for photocatalytic water splitting. However, all of the CTFs only are in the form of AA stacking model to participate in water splitting. Herein, two CTF-1 isomers with different stacking models (eclipsed AA, staggered AB) were obtained by modulating the reaction temperature. Interestingly, experimental and theoretical calculations showed that the crystalline AB stacking CTF-1 possessed a much higher activity for photochemical hydrogen evolution (362 μmol g−1 h−1) than AA stacking CTF-1 (70 µmol h−1 g−1) for the first time. The outstanding photochemical performance could be attributed to its distinct structural feature that allows more N atoms with higher electron-withdrawing property to be involved in the water reduction reaction. Notably, as a cathode material for PEC water reduction, AB stacking CTF-1 also demonstrated an excellent saturated photocurrent density up to 77 µA cm−2 at 0 V vs. RHE, which was superior to the AA stacking CTF-1 (47 µA cm−2). Furthermore, the correlation between stacking models and photocatalytic H 2 evolution of CTF-1 were investigated. This study thus paves the path for designing optimal photocatalyst and extending the novel applications of CTF-based materials. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ag2S-sensitized TiO2 films show good photoelectric responses in visible-light region. [•] Frequency-modulated SPV give dynamic information and evidence of Ag2S QDSSCs’ performance. [•] Frequency-modulated SPV can supply complementary information in the study of Ag2S ODSSCs. [ABSTRACT FROM AUTHOR]

Abstract: Ag–ZnO nanorods with enhancement in UV light photoelectric gas-sensing response properties were synthesized by a facile two-step process and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution electron microscope (HRTEM) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The results revealed that Ag nanoparticles have decorated the surface of ZnO nanorods successfully. Formaldehyde (HCHO) sensing properties of sensors based on the Ag–ZnO nanorods were also investigated under 370nm light irradiation at room temperature with the assistance of surface photocurrent technique. It was found that the as-prepared Ag–ZnO nanorods showed excellent gas-sensing property that the gas response to 5 and 40ppm formaldehyde can reach to 9.4% and 119.8% under 370nm light irradiation at room temperature, respectively. To better understand the reason for the enhanced gas-sensing properties of Ag–ZnO, the separation and transfer behavior of the photogenerated charges were characterized by means of surface photovoltage and phase spectra. The results indicated that an electronic interaction between Ag and ZnO formed. Ag, as electron acceptor, effectively promoted the charge separation and transfer ability and, at the same time, inhibited the recombination of photogenerated charge carriers in ZnO, thus the Ag–ZnO nanorods had a high gas-sensing response to HCHO at room temperature. [Copyright &y& Elsevier]

MOF-derived catalysts with well-defined morphology have garnered significant interest and research in their potential applications in the fields of photocatalysis and electrocatalysis. In the article, a neoteric and promising photocatalytic system of CoTiO 3 /MOF-derived In 2 S 3 type-Ⅱ heterogeneous catalyst with different weight percentages was prepared by a simple hydrothermal method. The system displayed remarkable photocatalytic and electrocatalytic properties. Under optimal conditions, the CoTiO 3 /MOF-derived In 2 S 3 catalyst achieved a high photocatalytic degradation efficiency within 30 min for terramycin, tetracycline hydrochloride (TCH), Rhodamine B (RhB), methylene blue (MB), bright blue (BB) and methyl orange (MO). The respective degradation efficiencies were 91.07%, 87.77%, 99.85%, 99.78%, 97.85%, and 93.94%. In addition, when subjected to H 2 evolution reaction (HER) at a current density of 10 mA/cm2, CoTiO 3 /MOF-derived In 2 S 3 (65 mV) demonstrated superior electrocatalytic performance compared to pure CoTiO 3 (429 mV) and MOF-derived In 2 S 3 (109 mV). Surprisingly, cyclic voltammetry yielded an electrochemical active area of 62 cm2, further confirming the enhanced electrochemical performance of CoTiO 3 /MOF-derived In 2 S 3. The results of the characterization indicate that design of type-Ⅱ heterostructure significantly enhances the specific surface area and interfacial charge transfer. In addition, the results of liquid chromatography-mass spectrometry (LC-MS) revealed the degradation intermediates of RhB and suggested its possible degradation pathways. This lays a solid foundation for the development of catalysts which are viable for use in both photocatalysis and electrocatalysis. [Display omitted] • CoTiO 3 /MOF-In 2 S 3 type-Ⅱ composites was prepared successfully for the first time. • MOF-derived composites with well-defined morphology show high specific surface area. • CoTiO 3 /MOF-In 2 S 3 composites can be effectively used to degrade various pollutants and electrolytic water. • The degradation pathway of RhB was analyzed by LC-MS. [ABSTRACT FROM AUTHOR]

The photogenerated hole transfer from the bulk to the surface is highly valued in the rational design of advanced photoanodes. However, the transfer of photogenerated electrons to the FTO (fluorine-doped tin oxide glass) substrate has a vital influence on the separation behaviors of photogenerated charges as well, which would regulate the photoelectrochemical (PEC) performance of photoanodes in turn. Herein, the W-TiO 2 /Ti-Fe 2 O 3 heterojunction was fabricated for the first time by inserting W-TiO 2 as the electron transfer layer between the Ti-Fe 2 O 3 photoanode and the FTO substrate. Benefitting from the unique electron transport channel of W-TiO 2 , the photogenerated electrons in Ti-Fe 2 O 3 could smoothly migrate to FTO, while photogenerated holes water oxidation kinetics is promoted and then easily participate in water oxidation reaction. As expected, W-TiO 2 /Ti-Fe 2 O 3 exhibits a remarkable negative onset potential and a slight improved photocurrent density. [Display omitted] • The charge transport of Ti-Fe 2 O 3 is modulated by inserting W-TiO 2 electron transfer layer at the Ti-Fe 2 O 3 /FTO interface. • The W-TiO 2 assist photogenerated electrons transfer to FTO rapidly, and suppress the recombination in the bulk photoanode. • W-TiO 2 accelerates more photogenerated holes in Ti-Fe 2 O 3 to participate in PEC water oxidation reaction. • 6W-TiO 2 /Ti-Fe 2 O 3 exhibits a remarkable negative onset potential of 140 mV, in comparison with that of Ti-Fe2O 3. [ABSTRACT FROM AUTHOR]

Charge separation and transfer are central issues dominating the underlying energy conversion mechanisms of photosynthetic systems. Here, inspired by nature, a multi‐interfacial engineering strategy for constructing a strongly coupled interactive transmission network for stable and efficient photocatalytic hydrogen production is proposed. A multivariate all‐solid‐state Z‐scheme with intimate electron interactions is formed through strong bridging bonds due to Ti orbit modulation and stacking hybridization between hybrids. The electron couple structure realizes an efficient carrier directional separation and transfer, enabling the charge separation efficiency to be enhanced dramatically by 7.2 times. Furthermore, the resulting material provides a highly stable photocatalytic hydrogen activity, up to 15.29 mmol h−1 g−1, 18.8 times higher than pure carbon nitride, surpassing many reported photocatalysts. This work represents a significant development and helps develop a sound foundation for future design principles in accelerating charge transfer. [ABSTRACT FROM AUTHOR]

Decorating a high-efficiency oxygen evolution reaction (OER) electrocatalyst as a cocatalyst on an α-Fe2O3 photoanode is known to be one of the most efficient methods to improve the photoelectrochemical (PEC) water oxidation activity. In our work, different from traditional methods of transition metal sulfide cocatalyst synthesis, an NiFeSx–decorated Ti-Fe2O3 photoanode is synthesized through a simple one-step electrodeposition method, which benefits the interface between Ti-Fe2O3 and NiFeSx. With the help of this excellent OER electrocatalyst, the photocurrent density of the NiFeSx–Ti-Fe2O3 photoanode rises to 3 mA cm−2 at 1.23 V vs. RHE, which is 2.5 times greater than the photocurrent of Ti-Fe2O3. Moreover, the onset potential of NiFeSx–Ti-Fe2O3 shifts negatively by 170 mV compared with that of pure Ti-Fe2O3. Furthermore, surface photovoltage spectroscopy (SPV) and transient photovoltage (TPV) techniques and photoelectrochemical impedance spectroscopy (PEIS) were used to analyze the true effects of NiFeSx as an efficient cocatalyst for enhancing the PEC performance of the NiFeSx–Ti-Fe2O3 photoanode. This work provides a simple method for loading a low-cost and efficient cocatalyst to modify a Ti-Fe2O3 photoanode for the PEC water oxidation reaction. [ABSTRACT FROM AUTHOR]

Abstract: Different sizes of ZnWO4 photocatalysts were synthesized by a hydrothermal method. The as-prepared sample shows highly efficient photocatalytic activity for the degradation of RhB under UV irradiation, which significantly vary with the increase of the hydrothermal temperatures. Surface photovoltage spectrum (SPS), field-induced surface photovoltage spectrum (FI-SPS) and surface photovoltage transient (TPV) techniques are used to investigate the detailed photoinduced charge transfer behavior. Results indicate that the ZnWO4 synthesized at 413K possess the largest BET surface area and the abundant donor surface states which are assumed to inhibit the recombination of the photogenerated electron–hole pairs, and thus a significant enhancement in the reaction rate is observed. [Copyright &y& Elsevier]

• Magnetic p-n Bi 2 WO 6 /CuFe 2 O 4 for efficient photo-Fenton-like was fabricated. • Different ROS-dominated dark-and photo-Fenton-like reactions were explored. • Possible degradation pathways of TCH and products toxicity were analyzed. The extensive use of tetracycline hydrochloride (TCH) poses a threat to human health and the aquatic environment. Here, magnetic p-n Bi 2 WO 6 /CuFe 2 O 4 catalyst was fabricated to efficiently remove TCH. The obtained Bi 2 WO 6 /CuFe 2 O 4 exhibited 92.1% TCH degradation efficiency and 50.7% and 35.1% mineralization performance for TCH and raw secondary effluent from a wastewater treatment plant in a photo-Fenton-like system, respectively. The remarkable performance was attributed to the fact that photogenerated electrons accelerated the Fe(III)/Fe(II) and Cu(II)/Cu(I) conversion for the Fenton-like reaction between Fe(II)/Cu(I) and H 2 O 2 , thereby generating abundant •OH for pollutant oxidation. Various environmental factors including H 2 O 2 concentration, initial pH, catalyst dosage, TCH concentration and inorganic ions were explored. The reactive oxidation species (ROS) quenching results and electron spin resonance (ESR) spectra confirmed that •O 2 − and •OH were responsible for the dark and photo-Fenton-like systems, respectively. The degradation mechanisms and pathways of TCH were proposed, and the toxicity of products was evaluated. This work contributes a highly efficient and environmentally friendly catalyst and provides a clear mechanistic explanation for the removal of antibiotic pollutants in environmental remediation. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen vacancies were introduced to regulate the microstructure of carbon nitrogen and facilitate co-catalyst loading. • Nitrogen vacancies were beneficial to capture [PtCl6]2- and reduce [PtCl6]2- by photo-generated electrons, hence stabilizing Pt ultra-small clusters. • The interaction between nitrogen vacancies and Pt ultra-small clusters was unveiled by test of field scanning steady state surface photovoltage (fs-SPV). • The interaction between nitrogen vacancies and Pt ultra-small clusters improves the sluggish kinetics of electron transfer, boosting photocatalytic hydrogen production. Tuning the microstructure of the catalyst surface is crucial for the loading of the co-catalyst, especially influencing the electron transfer and the size of the co-catalyst. However, influence of co-catalyst loading, related to the surface structure of the catalysts, is largely ignored. Here in, nitrogen vacancies were introduced to regulate the microstructure of carbon nitrogen and using this amorphous carbon nitride (ACN) with nitrogen vacancies as a substrate to provide atomic anchoring sites as well as electron sink to prevent Pt from further agglomeration. Experimental and theoretical results show that nitrogen vacancies were electron acceptors, which beneficial to reduce [PtCl 6 ]2− by photo-generated electrons and consequently stabilize Pt ultra-small clusters located on the ACN. Furthermore, by combing structure and carrier behaviors, we infer that Pt ultra-small clusters stable location comes from the strong interaction between Pt and nitrogen vacancies. Pt ultra-small clusters improve electron transfer and boost photocatalytic hydrogen production. A delicate design modulates the catalyst microstructure to enhance interaction between the catalyst and the co-catalyst, resulting in a smaller co-catalyst size and provides a mean to create and optimize small size Pt-loaded and highly active photocatalysts. [ABSTRACT FROM AUTHOR]

• A series of N-TiO 2 /Mn-HPMo/Ag samples were synthesized by photoreduction method for the degradation of Rhodamine B. • The N-TiO 2 /Mn-HPMo/Ag-300 exhibited superior photocatalysis-Fenton activity. • Ag deposition enhanced the visible light absorption of the catalyst. • Ag deposition provided a large number of electrons for the generation of reactive radicals. In this paper, Ag nanoparticles were deposited on the surface of nitrogen-doped titanium dioxide coupled with manganese-substituted phosphomolybdic acid composites (N-TiO 2 /Mn-HPMo) using photoreduction method to construct ternary photocatalysis-Fenton composite catalyst (N-TiO 2 /Mn-HPMo/Ag), and the degradation performance of the catalyst was evaluated with Rhodamine B (RhB) as the target pollutant. The results showed that the N-TiO 2 /Mn-HPMo/Ag ternary composite catalyst had remarkable visible light activity, and the degradation efficiency of RhB could reach 96.3% in 20 min under visible light. Meanwhile, UV–vis diffuse reflectance spectroscopy illustrated the promotion effect of Ag deposition on the visible light response of N-TiO 2 /Mn-HPMo. The behavior of photogenerated charges was also characterized by Surface Photovoltage Technique, which further demonstrated that Ag deposition not only extended the light absorption range but also enhanced the separation efficiency of photogenerated charges. This work provides favorable information for the construction of efficient catalysts with high activity under visible light. [Display omitted] [ABSTRACT FROM AUTHOR]

Doping graphitic carbon nitride (g-C3N4) with metal ions has been developed as a facile approach to improve its visible light photocatalytic performance towards hydrogen evolution via water splitting. In this work, a series of In3+ doped g-C3N4 (In-g-C3N4) photocatalysts were prepared via in situ thermal copolymerization by using a mixture of dicyanamide and InCl3 as precursors. It was proposed, for the first time, that the In3+ ions were doped into g-C3N4 in a unique quasi-interlayer fashion, which contributed to tunable separation efficiency and migration ability of the photogenerated carriers by simply adjusting the amount of In3+ doping without changing the band edge of g-C3N4. The In-g-C3N4 photocatalyst doped with an optimal amount of indium ions, i.e., 2.18 wt%, exhibited a hydrogen evolution rate of 1.35 mmol h−1 g−1, 17 times that of pristine g-C3N4 (0.08 mmol h−1 g−1), attributed to the synergistically promoted separation and migration of the photogenerated charge carriers. [ABSTRACT FROM AUTHOR]

By the aid of transient photovoltage, photo-generated carrier transfer mechanism of SnS 2 /g-C 3 N 4 composite has been suggested by interfacial electric field direction. Constructing heterojunction is an effective way to improve the photo-generated carrier separation efficiency and photocatalytic activity. Here, we construct SnS 2 /g-C 3 N 4 heterojunctions by in-situ growth of SnS 2 on the g-C 3 N 4. By adjusting annealing temperatures, the SnS 2 /g-C 3 N 4 -180 and SnS 2 /g-C 3 N 4 -120 samples could meet Z-scheme carrier transfer mechanism and conventional type-II charge transfer mechanism, respectively. By the aid of surface photovoltage spectra, the photo-generated carrier transfer direction and the driving force of the charge transfer are suggested. This difference in these two charge transfer mechanisms is supposed to be mainly related to the discrepancy in work functions of the SnS 2 treated at different temperatures. This work provides an effective method to understand the Z-scheme carrier transfer mechanism, which could help us to design Z-scheme photocatalysts for higher hydrogen evolution activity. [ABSTRACT FROM AUTHOR]

In this work, the ZnO/Cu 2−x S composite material is prepared based on Al doped zinc oxide glass substrate and applied as counter electrode (CE) in quantum dot sensitized solar cell. The ZnO/Cu 2−x S CEs with the different Cu/S ratios of Cu 2−x S (2-x = 1.73–1.48) can be controlled by immersing Cu/ZnO in different concentrations of S2- solution. As a result, the solar cell fabricated by Cu 1.62 S/ZnO CE exhibits the best photoelectric conversion efficiency of 5.35% under 1 sun illumination, which is higher than that of Cu 1.62 S CE (4.22%). On the basis of the result of solid-state current density–voltage test and transient photovoltage measurements, the formation of p-n heterojunction and the improving electrocatalytic activity in composite CEs accounts for the enhanced photoelectric conversion efficiency. These results are coincide with the outcomes of the impedance analysis, Tafel polarization measurement and cyclic voltammetry test for the symmetrical cell. Consequentially, the ZnO/Cu 2−x S composite counter electrode is a promising material and the applications in solar cells. • Cu 2−x S/ZnO CEs are fabricated by in-situ inward etching method. • The QDSCs based on the Cu 1.62 S/ZnO CE achieves the PCE of 5.35%. • The formation of heterojunction accounts for the enhanced Photovoltaic performance. • The energy band structures of heterojunction is investigated in composite CE. • The Cu 2−x S/ZnO CEs show excellent stability in polysulfide electrolyte. [ABSTRACT FROM AUTHOR]

Abstract: Monodisperse Ag/Anatase TiO2 core–shell nanoparticles were synthesized by a simple solvothermal method. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements confirm that the as-synthesized nanoparticles have the core–shell structure and TiO2 shell is anatase phase. Interestingly, the photocatalytic ability of the as-synthesized nanoparticles for degrading alizarin red (AR) is greatly increased compared with that of Dessuga P25. [Copyright &y& Elsevier]

A novel Pt/CeO2/ZnO ternary composite is synthesized via two simple procedures of hydrothermal and photoreduction. The crystal structure, morphology, and composition of as-prepared samples are characterized by XRD, SEM, HRTEM, XPS and UV–Vis DRS. Because both ZnO and CeO2 are good photocatalytic semiconductors, photocatalytic activities of the samples are evaluated by the degradation of phenol aqueous solution (25 mg/L). Under the strong interaction among the Pt, CeO2 and ZnO, the maximum photocatalytic activity is observed in the Pt/CeO2/ZnO ternary composites and 91% phenol can be degraded in 60 min under UV light irradiation. The probable photocatalytic mechanism is discussed by active species trapping experiments along with SPV, TPV, PL and PA measurements. The enhanced photocatalytic activity is attributed to the redox cycle of Ce4+ ↔ Ce3+, the effective interface between ZnO and CeO2 as well as the electron transfer action of Pt nanoparticles. The photocatalytic activity almost unchanged after four cycles and proves excellent reusable photocatalysts. This work shows the synergistic effect of rare earth elements and noble metals in the photocatalytic process, which facilitates their practical application in toxic pollution abatement. [ABSTRACT FROM AUTHOR]

• A new synthetic routes of Cu 2−x Se/CuTi CE has been proposed. • Cu 2−x Se/CuTi CE is fabricated by sacrifice template method. • The QDSCs based on the Cu 2−x Se/CuTi CE achieves the PCE of 6.25%. • The enhanced photovoltaic performance could be attributed to the improving electrocatalytic activity. • The Cu 2−x Se/CuTi CE shows excellent stability in polysulfide electrolyte. An efficient and simple strategy is designed for the synthesis of Cu 2−x Se with two different morphology, including networks nanostructure and nanosheets structure, based on Ti substrate using a sacrificial template method (CuTi 2 S 4 and Cu). The corresponding Cu 2−x Se/CuTi CE and Cu 2−x Se/Cu CE could be applied as counter electrodes (CE) for quantum dot sensitized solar cells (QDSCs). As a result, the cell fabricated by Cu 2−x Se/CuTi-4 CE exhibits a photoelectric conversion efficiency (PCE) of 6.25% under 1 sun (100 mW/cm2) illumination as compared to that of Cu 2−x Se/Cu CE (4.83%). According to transient photocurrent (TPC) result, the improving photovoltaic performance could be attributed to the improving electrocatalytic activity towards polysulfide electrolyte as compared to Cu 2−x Se/Cu CE. These results are in accordance with the EIS analysis and Tafel polarization curve results for symmetrical cell. In addition, the outstanding stability of Cu 2−x Se/CuTi CE could be further proved by cyclic voltammetry (CV) test. In conclusion, the Cu 2−x Se/CuTi CE could be a promising material and the applications in solar cells. [ABSTRACT FROM AUTHOR]

Inevitable drawbacks on α-Fe 2 O 3 photoanodes, such as poor conductivity, short hole diffusion length, high electron-hole recombination rate, limit their photoelectrochemical (PEC) performance for water oxidation. The construction of heterojunction is an effective approach to improve the PEC performance of photoanodes. Herein, we report the design of the WO 3 /Ti–Fe 2 O 3 heterojunction photoanodes, which are synthesized by two simple hydrothermal method. The optimized WO 3 /Ti–Fe 2 O 3 photoanode shows remarkably improved photocurrent of 2.15 mA/cm2 at 1.23 V versus reversible hydrogen electrode (RHE) without additional cocatalyst, which is higher than that of previous literatures. The improvement benefits from reduced charge transfer resistance in the bulk of Ti–Fe 2 O 3 photoanode and improved charge separation efficiency, which can been further confirmed by electrochemical impedance spectroscopy (EIS), the transient photovoltage (TPV) and the work function (WF) measurement. The present work also provide new opportunities in developing high performance photoanodes for PEC water splitting. WO 3 served as an electron transfer layer can reduce the resistance of interface charge transfer and improve the charge separation efficiency of Ti–Fe 2 O 3. However, charge separation efficiency is closely related to charge injection efficiency, therefore, more holes of Ti–Fe 2 O 3 will transfer to electrolyte to participate in the water oxidation. Image 1 • WO 3 served as an electron transfer layer can reduce the resistance of interface charge transfer. • The introduction of WO 3 can improve the charge separation efficiency of Ti–Fe 2 O 3. • The separation and transfer process of photogenerated charge carriers have been discussed. [ABSTRACT FROM AUTHOR]