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Photoelectrocatalysis has attracted significant attention for water splitting and contaminant degradation. However, the lifetime of photoelectrocatalysis devices is hampered by the severe instability and photocorrosion of the photo‐active nanomaterial on the photoelectrode, which is a key limitation to realizing industrialization. Typically, the conventional protection strategy of photoelectrodes usually suffers from the trade‐off between the photoelectrocatalytic activity and stability. Inspired by biological cell membrane with water channels, here a highly permeable and ultrathin silica coating with ultrasmall straight nanochannels is in situ grown that stabilizes the photoelectrode. These ultrasmall channels boost photoelectrocatalysis by accelerating water transport and reducing the reaction energy within the confined nanochannels. Specifically, the ultrathin coating imparts significant mechanical and structural stability to the photo‐active nanomaterial, thereby preventing its detachment, dissolution, and crystal damage without compromising performance. As a result, the protected photoelectrode exhibits enhanced water splitting activity and excellent stability over 120 h, whereas the photocurrent of the unprotected photoelectrode degrades rapidly. Meanwhile, the coated photoelectrode also exhibits superior photoelectrocatalytic degradation efficiency (>97%), even after the 10th cycle. This strategy is facile and universal and can be extended to construct other stable and high‐performance electrodes for promoting photoelectrocatalysis in practical applications. [ABSTRACT FROM AUTHOR]

Developing a nonprecious and sustainable electrocatalyst in clean energy generation is quite noteworthy. Transition metal chalcogenides, oxides, and phosphides have emerged as promising candidates to substitute Pt‐based catalysts. In this study, we explore the catalytic potential of ReS2, a promising member of the transition metal dichalcogenides (TMD) family, for hydrogen evolution reactions (HER). The formation of rhenium oxide during the synthesis of ReS2 and further incorporation of a bimetallic phosphide NiCuP in a sequential hydrothermal synthesis reveals an excellent HER activity, as demonstrated by photoelectrochemical and electrochemical studies. Notably, the catalyst exhibits a significantly lower overpotential of −0.10 V (corresponding to −10 mA/cm2) and achieves a high current density of approx. −271 mA/cm2 at −0.79 V versus reversible hydrogen electrode (RHE) under light irradiation. The catalyst demonstrates high stability. These findings underscore the potential of NiCuP‐integrated ReS2/Re2O7 as a highly efficient and sustainable catalyst for HER. [ABSTRACT FROM AUTHOR]

In the field of photocatalytic degradation, the separation and recycle technology of powdery g-C3N4 after usage has not been mature, which causes secondary pollution problems for large-scale industrial applications. In this paper, carbon-fiber/g-C3N4 nanosheet arrays were fabricated by chemical vapor deposition(CVD) under argon protection, and the optical, electrochemical and photocatalytic performance of carbon-fiber/g-C3N4 nanosheet arrays were studied. The results indicated that carbon-fiber/g-C3N4 nanosheet arrays generated photon-excited electrons and holes under visible light irradiation during photocatalytic process. The excellent electrical conductivity of carbon fiber could trap photon-excited electrons in conduction band of g-C3N4 nanosheet and creat holes in valence band of g-C3N4 nanosheet. 20.7%, 33.5% and 99.5% of 2, 4-dinitrophenol were degraded by photocatalysis, electrocatalysis and photoelectrocatalysis of carbon-fiber/g-C3N4 nanosheet arrays within 240 min. The external voltage further enhanced the separation of photo-generated electrons and holes, which made the photoelectrocatalysis of carbon-fiber/g-C3N4 nanosheet arrays exerted unexpected performance through synergistic interactions of photocatalysis and electrocatalysis. The assembly of powdery photocatalysts and carbon fibers textile might provide a general methodology in the design of separable and recyclable photocatalysts with broad applications in environment-related fields. The assembly strategy developed herein significantly reduced the separable and recyclable cost of powdery photocatalysts and offered valuables references for industrial application of photocatalysis and photoelectrocatalysis.

TiO 2 -based photoelectrocatalysts are synthesized by anodization at 90, 70 and 50V, using ethylenediamine to incorporate C and N elements (i.e. formation of coordinated complexes). The analysis is focused on determining the effects of oxygen vacancies, crystallite size, phase type, band gap size, elemental surface composition, roughness, and thickness of the photoelectrodes, to establish those influencing the photoelectroactivity of H 2 production. H 2 is generated with irradiations simulating solar conditions, and only visible-light. The photoelectrode formed at 70V develops the largest photocurrent, and consequently the largest H 2 production. It is revealed that the lowest content of oxygen vacancies, the highest amount of elemental C and O at the surface, and the reduction of the main band gap in this photoelectrode substantially control the photoactivity of this reaction. While the roughness and thickness of the coatings, the crystallite size, the specific surface area, and the surface compositions of elemental Ti and N are found to be negligible. [Display omitted] • Ethylenediamine was effective to incorporate C and N species into anodized TiO 2. • C and N incorporations reduced the main band gaps of all (CN)–TiO 2 photoanodes. • Oxygen vacancies, surface contents of C and O, and band gap size control H 2 yield. • Roughness, thickness, and crystallite size of catalysts do not impact H 2 activity. • Specific area and surface compositions of Ti and N are negligible for H 2 generation. [ABSTRACT FROM AUTHOR]

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Herein, the photoelectrocatalytic and photocharging activity of a Ni3TeO6 (NTO‐700) photoelectrocatalyst for water oxidation in alkaline medium is demonstrated and calcined at 700 °C. The photoelectrocatalytic (PEC) activity of the sample is increased upon an increase in the illumination time. With a twofold increase in photocurrent density at 1.8 V, the PEC 150 sample (having been illuminated for 150 min) attained the highest PEC activity. The synthesized material has displayed an excellent charge storage capacity in KOH and Na2SO4 electrolyte solutions (both 0.1 m). The chrono‐amperometry measurement, subsequent to light interruption, has sustained almost 44% higher current density (even after 200 min) compared to the pure electrocatalytic baseline in a Na2SO4 electrolyte. The charge transfer resistance, Rct, decreases from 633.40 to 170.40 Ω, while the charge transfer rate constant, kct, increases from 7.93 to 27.03 s−1, as a function of illumination time. This points to fast separation of electron–hole (e−–h+) pairs and a slower recombination rate. The lower values of the charge transfer resistance and the time constant recorded for the light interrupted samples, as compared to the electrochemical sample, are attributed to the stored charge that drives water oxidation at a higher rate. [ABSTRACT FROM AUTHOR]

Despite being an indispensable medium for life and the environment, the deterioration of water quality continues to be a matter of great concern for the scientific community since this problem has generated the need to develop processes for water treatment. Among the wide variety of types of contaminants, the presence of contaminants of emerging concern (CECs) has become an issue of global concern, since they are present in water in low concentrations and can persist in the environment, bioaccumulate and be toxic to human health and aquatic biota. Among CECs, this review focuses on pharmaceutical removal; what favorable effects they have on human and animal health are widely recognized, but the consequences or risks associated with the constant disposal of these products to the environment, through the manufacturing process, consumption, biological excretion or inappropriate disposal, are an area under constant study. The presence of pharmaceuticals in water represents a high risk to the environment because they contain active ingredients that were designed to induce specific pharmacological effects but, when dissolved in water, reach non-target populations and cause undesirable toxicological effects. This review pays attention to the photoelectrochemical removal of paracetamol (PTM), as a model molecule, from water, employing different photoactive materials (TiO2, BiVO4, ZnO and tungsten oxides) and the main parameters affecting their performance. The main goal of the present review is to facilitate future researchers to design their experiments concerning the PEC processes for the degradation of pharmaceuticals, specially PTM, and the existing limitations of each system. [ABSTRACT FROM AUTHOR]

As an intriguing strategy for massive hydrogen production, photoelectrochemical (PEC) seawater splitting compels the anode to be highly hypochlorite-resistant. Inspired by algae, we designed a robust photoelectrocatalyst that WO 3 nanorods (NRs) are covered by N/W co-doped (Co, Ni, W)O x N y nanosheets (NSs). The NSs expose (111) faces and are decorated by (Co, Ni)WO 4 nanoparticles. DFT calculations reveal that Co and Ni atoms on the (111) surface of N/W co-doped NSs are more likely to adsorb OH-, while W atoms are more favorable to adsorb Cl-. Secondly, the lattice distortion and multi-crystal phases of NSs are triggered by doped W atoms, and the evacuation of 5d electrons makes W atoms as donor centers, leading to enhanced catalytic activity of CoNi atoms and corrosion resistance to Cl-. Furthermore, the N atoms expand the valence band of CoNiO x and elevate the conduction band of (Co, Ni)WO 4 , facilitating more electrons to participate in PEC reaction and the realization of seawater full-splitting. Resultantly, the N/W co-doped (Co, Ni, W)O x N y /WO 3 hetero-NRs (HNRs) demonstrate a PEC current density about 0.35 mA/cm2 at 1.23 V RHE with durability over 100 hours in seawater. This work provides a practical strategy towards the durable PEC anode for seawater splitting. [Display omitted] • The (Co, Ni, W)O x N y /WO 3 has robust photocurrent and durability in seawater. • Exposed (111) face of N/W doped CoNiO x has adsorption selectivity of OH- and Cl-. • N-doping optimizes the band structures of CoNiO x and (Co, Ni)WO 4. • It provides a Cl--resistant strategy towards photoelectrocatalytic seawater splitting. [ABSTRACT FROM AUTHOR]

Integration of non-noble transition metal oxides with graphene is known to construct high-activity electrocatalysts for oxygen evolution reduction (OER). In order to avoid the complexity of traditional synthesis process, a facile electrochemical method is elaborately designed to engineer efficient WO3-x/graphene (photo-)electrocatalyst for OER by a two-electrode electrolysis system, where graphite cathode is exfoliated into graphene and tungsten wire anode evolves into VO-rich WO3-x profiting from formed reductive electrolyte solution. Among as-prepared samples, WO3-x/G-2 shows the best electrocatalytic performance for OER with an overpotential of 320 mV (without iR compensation) at 10 mA/cm2, superior to commercial RuO2 (341 mV). With introduction of light illumination, the activity of WO3-x/G-2 is greatly enhanced and its overpotential decreases to 290 mV, benefiting from additional reaction path produced by photocurrent effect and extra active sites generated by photogenerated carriers (h+). Characterization results indicate that both VO-rich WO3-x and graphene contribute to the efficient OER performance. The activity of WO3-x for OER is decided by the synergistic effect between VO concentration and particle size. The graphene could not only disperse WO3-x nanoparticles, but also improve the holistic conductivity and promote electron transmission. This work supports a novel method for engineering WO3-x/graphene composite for highly efficient (photo-)electrocatalytic performance for OER. [ABSTRACT FROM AUTHOR]

Semiconductors as photoelectric catalysis is recognized as a promising strategy for simultaneous face energy crisis and environmental pollution. In this study, amorphous silicon carbide (SiC) thin films were deposited on Si (100) by reactive direct current magnetron sputtering at room temperature of high purity silicon carbide 6H SiC target. By DRX and EPMA analysis, we confirmed the amorphous character of silicon carbide thin layers and the stoichiometric chemical composition respectively. The FTIR measurement confirms the presence of Si–C, Si–Si and Si–O bonds. The peak corresponding to Si–C was found about 777 cm−1. The optical properties were conducted and the optical gap (Eg = 2.236 eV) was determined. The electrochemical properties of amorphous silicon carbide thin films on p-Si substrate were studied and confirmed a p type electrode. By CPG analysis, the conversion of CO2 to methanol was confirmed using silicon carbide as a working electrode. Based on the found results, the SiC@Si based electrode could actually be used as a photocathode for the PEC reduction of CO2 into added value organıc components such as methanol. [ABSTRACT FROM AUTHOR]

The application of Ag as an electrocatalyst for hydrogen evolution reaction (HER), which holds promise to quench the worldwide thirst for clean energy source, is severely limited by its poor intrinsic activity. To address this issue, in the present contribution the Ag electrode is anodically etched, giving rise to the Ag nanocorals (NCs) consisted of closely interconnected Ag nanoparticles (NPs), between which the grain boundaries are flooded with coordinately unsaturated Ag atoms. Electrokinetic studies reveal that those under–coordinated Ag atoms stabilize the hydrogen intermediates bound to Ag NCs to facilitate the subsequent transfer of the hot electrons stemmed from the relaxation of the localized surface plasmon resonance (LSPR) of Ag NCs under visible and near–infrared (NIR) light illumination. As a result of such synergistic effect is HER over Ag NCs largely accelerated, resulting in the cathodic current density of 10 mA cm−2 readily turned on at an early overpotential η = 156 mV with respect to those of additional Ag-based electrocatalysts reported in the literature. Such outperformance unambiguously highlights the strong prospect of Ag NCs as an alternative photoelectrocatalyst, which additionally takes advantage of the incident light to boost HER, to the state–of–the–art Pt electrocatalytic counterpart for solar fuel production. [Display omitted] • Ag NCs made of interconnected NPs is put forward as efficient HER electrocatalyst. • Ag NCs exhibits a Tafel slope of 79 mV dec−1 and an overpotential (η 10) of 156 mV. • Mechanistic insight is provided by a microkinetic model coupled with FDTD simulation. • Dissociated adsorption of H 3 O+ on Ag NCs is promoted by under–coordinated Ag atoms. • HER is accelerated by LSPR–induced hot electrons of Ag NCs under light illumination. [ABSTRACT FROM AUTHOR]

Bi2S3 nanostructures with various morphologies were synthesized through hydrothermal vulcanization at different sulfur precursor (thiourea) concentrations. A 100 nm thick sputter-deposited Bi2O3 thin-film layer on a fluorine-doped tin oxide glass substrate was used as a sacrificial template layer. The etching of the Bi2O3 sacrificial template layer and the regrowth of Bi2S3 crystallites during hydrothermal vulcanization produced the different Bi2S3 nanostructure morphologies. The lowest sulfur precursor concentration (0.01 M) induced the formation of Bi2S3 nanosheets, whereas the Bi2S3 nanoribbons and nanowires were formed with increased sulfur precursor concentrations of 0.03 and 0.1 M, respectively. These results indicate that sputter-deposited Bi2O3 thin-film layers can be effectively used to form low-dimensional Bi2S3 crystals with controllable morphologies. Among the various Bi2S3 samples, the Bi2S3 nanosheets exhibited superior photoactive ability. The higher active surface area, surface defect density, light absorption capacity, and photo-induced charge separation ability of Bi2S3 nanosheets explain their superior photoelectrocatalytic degradation ability of rhodamine B dyes.

Solar energy is a clean and abundant energy source. In a photoelectrochemical cell, energy from sunlight is captured and converted into electric power, chemical fuels such as hydrogen is employed to degrade organic pollutants. ZnO is a promising material for photoelectrocatalysis due to its remarkable properties. The aim of this review is to perform an exhaustive revision of nanostructured ZnO synthesis by electrochemical anodization in order to control surface characteristics of this material through anodization parameters such as electrolyte type and concentration, potential, time, temperature, stirring, and post treatment. Finally, application of ZnO nanostructures is overviewed to observe how surface characteristics affected the ZnO photoelectrocatalytic performance. [ABSTRACT FROM AUTHOR]

The addition of Re 2 O 7 to bulk MoS 2 followed by thermal treatment effectively generates a p-n junction MoS 2 -MoO 3 -Re 2 O 7 composite which accelerates the electrochemical and photoelectrochemical hydrogen evolution reaction of bulk MoS 2. [Display omitted] Two-dimensional transition metal dichalcogenides (TMD) are promising cost-effective catalysts for electrochemical/photoelectrochemical hydrogen evolution reactions (HER). One of the strategies to enhance the inherent HER activity of a catalyst is to form heterostructures. Herein, a facile thermal treatment method is reported for the synthesis of a novel heterostructure catalyst, Molybdenum disulphide-Molybdenum trioxide-Rhenium oxide (MoS 2 -MoO 3 -Re 2 O 7), for HER. MoS 2 -MoO 3 -Re 2 O 7 composite is prepared using bulk MoS 2 , which is otherwise known as a weak HER catalyst. Electrochemical and photoelectrochemical studies substantiate the enhanced catalytic activity of the MoS 2 -MoO 3 -Re 2 O 7 composite than the MoS 2 bulk towards HER. The Mott-Schottky analysis suggests the formation of p-n heterojunction, which offers large interfacial contact and facilitates easier charge separation and transfer of photogenerated charge carriers resulting in an improved photoelectrocatalytic activity. The catalyst exhibits excellent stability, confirmed by the repeated cycles of reaction. [ABSTRACT FROM AUTHOR]

Abstract Growing attention to the development of sustainable solar‐to‐energy conversion applications has resulted in the synthesis of promising and environment‐friendly nanomaterials as energy harvesters. Among various carbon nanomaterials, carbon dots (CDs) have received significant attention due to their excellent light absorption capability, broad absorption region, and superior photostability with enormous potential for solar energy applications. Therefore, utilizing and modulating the charge carriers generated from CDs is critical for achieving a high energy conversion efficiency of CDs. Herein, we focus on the distinct characteristics of CDs as energy converters from charge excitation to charge separation and transfer for various solar‐to‐energy applications, including photovoltaic cells, photocatalysts, and photoelectrocatalysts. We anticipate that this review will offer insight into the synthesis and design of novel nanocomposites with a fundamental analysis of the photochemical properties and future development of energy conversion devices.

Highly ordered TiO2 nanotubes (TNTs) decorated with a series of lanthanide ions (Ln3+ = Ho3+, Tb3+, Eu3+, Yb3+, and Er3+) were prepared through an electrochemical process and anodization. The composition, structure, and chemical bond of the as-prepared photocatalysts were characterized through scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and ultraviolet diffuse reflectance spectroscopy. Furthermore, the electrochemical characteristics of the catalysts were analyzed and photoelectrochemical properties were investigated through water splitting. All samples were prepared in the anatase phase without changing the crystal structure. The holmium-doped TNT photocatalyst exhibited the best performance with a hydrogen evolution rate of 90.13 μmol cm−2h−1 and photoconversion efficiency of 2.68% (0 V vs. RHE). Photocatalytic efficiency increased because of the expansion of the absorption wavelength range attributed to the appropriate positioning of the band structure and reduced electron/hole pair recombination resulting from the unhindered electron movement. This study demonstrated the preparation of high-potential solar-active photocatalysts through the synergetic effects of the work function, band edge, and bandgap changes caused by the series of lanthanide combinations with TNTs. [ABSTRACT FROM AUTHOR]

A novel photoelectrocatalyst composed from multiwalled carbon nanotubes (MWCNTs), titanium dioxide (TiO2) and gold-platinum bimetallic nanoparticles (Au-PtNPs) was prepared on the surface of a fluorine-tin oxide (FTO) electrode and it was used for electrooxidation of ethanol molecules. Multiwalled carbon nanotubes were utilized as the catalyst support to improve the electrical transmission. The TiO2 nanoparticles were transferred onto the surface of MWCNTs/FTO modified electrode and then, the surface of the electrode was coated with gold-platinum nanoparticles. The surface morphology and chemical composition of the prepared Au-Pt/TiO2/MWCNTs photoelectrocatalyst were characterized using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. The fabrication process of the photoelectrocatalyst was investigated by cyclic voltammetry and chronoamperometry techniques. The exchange current densities (J0) were calculated for Pt/FTO, Pt/MWCNTs/FTO, Pt/TiO2/MWCNTs/FTO and Au-Pt/TiO2/MWCNT/FTO electrodes and they were found to be: 4.10 × 10-5, 6.06 × 10-5, 1.45 × 10-4 and 1.89 × 10-4 mA cm-2, respectively. Also, the values of J0 for Pt/TiO2/MWCNTs/FTO and Au-Pt/TiO2/MWCNTs/FTO in the presence of light were obtained 2.0 × 10-4 and 5.1 × 10-4 mA cm-2, respectively. The obtained results reveal that the Au-Pt/TiO2/MWCNTs/FTO electrode has the higher J0 value in the presence of UV-Vis light and the light irradiation can accelerate the ethanol oxidation process. The experimental results showed that the proposed photoelectrocatalyst has an excellent catalytic activity for oxidation of ethanol molecules under the UV-Vis light irradiation which is due to the synergistic effect between the TiO2 photocatalyst and gold-platinum electrocatalyst. [ABSTRACT FROM AUTHOR]

Metallic photoelectrocatalysts possess a wide light absorption range and the fast hydrogen evolution reaction (HER) kinetics, which can be used as the next generation of catalysts towards photoelectrocataytic HER. In this work, molybdenum nitride has been fabricated via an in-suit growth method on metal molybdenum substance (Mo 3 N 2 /Mo foil). The metallic and optical property of Mo 3 N 2 was confirmed by the DFT calculations and experimental results from UV–visible absorption spectrum and valence X-ray photoelectron spectroscopy spectrum. Photocatalytic HER rate of Mo 3 N 2 reached to 158.78 μmol h−1 g−1. Furthermore, Mo 3 N 2 –MoS 2 /Mo foil was prepared to improve photoelectrocatalytic performance. Herein, a suitable energy band alignment for Mo 3 N 2 –MoS 2 /Mo foil was proposed based on experiments and DFT calculations, and the formation of a heterojunction (Mo 3 N 2 –MoS 2) effectively suppressed the recombination of photo-generated carriers. The results of photoelectrocatalytic experiments suggested that the photocurrent density of Mo 3 N 2 –MoS 2 /foil was effectively enhanced about 1.5 times than that of simplex Mo 3 N 2 /Mo foil. The electrochemical experiments (LSV and EIS) indicated that the metallic nature of Mo 3 N 2 was also beneficial to electrocatalytic HER, and the overpotential of Mo 3 N 2 –MoS 2 /Mo foil at 10 mA cm−2 was −173 mV. This work provides a potential candidate for photoelectrocatalytic electrodes. [Display omitted] • Metallic Mo 3 N 2 plays a dominant role in photoelectrocatalytic HER activity. • The metallic and optical nature were verified by experiments and DFT calculation. • Mo 3 N 2 –MoS 2 heterojunction was used to improve the photoelectrocatalytic property. • Schottky barrier effectively suppress the recombination of photoinduced carriers. • Mo 3 N 2 –MoS 2 /Mo foil electrode exhibits superior stability for HER. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel heterojunction photoelectrodes, TiO 2 nanorods sensitized by ZIF-9 were synthesized. • It extended the light absorption towards visible light and stimulated efficient charge separation. • Exhibited four times higher current density (0.94 mA/cm2) than titania nanorods with an applied bias to photon efficiency (ABPE) of 0.27 %. Traditional photocatalysts suffer from inferior utilization of solar light. Therefore, developing novel photocatalyst for better solar light harvesting is much required in the wake of current environmental problems arising from conventional energy technologies. Here we report synthesis and characterization of photocatalysts based on TiO 2 nanorods (TNR) and Zeolitic Imidazolate Framework-9 (ZIF-9) and their photoelectrochemical properties. The TNRs were sensitized by ZIF-9 through solvothermal method. The presence of ZIF-9 on TNR formed a p-n heterojunction which assisted in initiating efficient charge separation and promoting injection of these carriers into the electrolyte. The heterojunction catalysts also exhibited enhanced optical properties in terms of extended absorption with reduced bandgap in comparison to the TNR film. The aforementioned properties manifested in improved photoelectrochemical performance with a current density of 0.94 mA/cm2, which is four times better than TNR and an applied bias photon to current efficiency (ABPE) of 0.27 %, which is five times better than TNR film alone. These superior properties of the processed ZIF-TNR demonstrate their potential for photoelectrochemical catalysis, thus paving the way for green hydrogen generation. [ABSTRACT FROM AUTHOR]

The growing consumption of global energy has posed serious challenges to environmental protection and energy supplies. A promising solution is via introducing clean and sustainable energy sources, including photoelectrochemical hydrogen fuel production. 2D materials, such as transition metal trichalcogenphosphites (MPCh3), are gaining more and more interest for their potential as photocatalysts. Crystals of transition metal selenophosphites, namely MnPSe3, FePSe3 and ZnPSe3, were tested as photocatalysts for the hydrogen evolution reaction (HER). ZnPSe3 is the one that exhibited the lowest overpotential and the higher response to the light during photocurrent experiments in acidic media. For this reason, among the crystals in this work, it is the most promising for the photocatalyzed production of hydrogen.

Growing attention to the development of sustainable solar‐to‐energy conversion applications has resulted in the synthesis of promising and environment‐friendly nanomaterials as energy harvesters. Among various carbon nanomaterials, carbon dots (CDs) have received significant attention due to their excellent light absorption capability, broad absorption region, and superior photostability with enormous potential for solar energy applications. Therefore, utilizing and modulating the charge carriers generated from CDs is critical for achieving a high energy conversion efficiency of CDs. Herein, we focus on the distinct characteristics of CDs as energy converters from charge excitation to charge separation and transfer for various solar‐to‐energy applications, including photovoltaic cells, photocatalysts, and photoelectrocatalysts. We anticipate that this review will offer insight into the synthesis and design of novel nanocomposites with a fundamental analysis of the photochemical properties and future development of energy conversion devices. [ABSTRACT FROM AUTHOR]

As a new member of the carbon family, graphdiyne is an intrinsic semiconductor featuring a natural bandgap, which endues it potential for direct application in photoelectric devices. However, without cooperating with other active materials, conventional hexacetylene-benzene graphdiyne (HEB-GDY) shows poor performances in photocatalysis and photoelectric devices due to its non-ideal visible light absorption, low separation efficiency of the photogenerated carriers and insufficient sites for hydrogen production. Herein, we report a molecular engineering strategy for the regulation of GDY-based carbon materials, by incorporating a strong pyrene absorption group into the matrix of graphdiyne, to obtain pyrenyl graphdiyne (Pyr-GDY) nanofibers through a modified Glaser-Hay coupling reaction of 1,3,6,8-tetraethynylpyrene (TEP) monomers. For comparison, phenyl graphdiyne (Phe-GDY) nanosheets were also constructed using 1,3,4,6-tetraethynylbenzene (TEB) as a monomer. Compared with Phe-GDY, Pyr-GDY exhibits a wider visible light absorption band, promoted efficiency of the charge separation/transport and more sufficient active sites for water reduction. As a result, Pyr-GDY alone displays superior photoelectrocatalytic performance for water splitting, giving a cathode photocurrent density of ~138 μA cm−2 at a potential of −0.1 Vversus normal hydrogen electrode (NHE) in neutral aqueous solution, which is almost ten and twelve times as high as those of Phe-GDY (14 μA cm−2) and HEB-GDY (12 μA cm−2), respectively. Such a performance is also superior to those of most reported carbon-based metal-free photocathode. The results of theoretical calculations reveal that the carbon atoms in the acetylene bonds are the active sites for proton reduction. This work offers a new strategy for the construction of graphdiyne-based metal-free photo-electrocatalysts with enhanced photoelectrocatalytic performance. [ABSTRACT FROM AUTHOR]

2,2′:6′,2′′‐Terpyridine (tpy) and its derivatives represent highly versatile ligands for the complexation of transition metal ions. Today, such complexes are employed in a highly diverse fashion – including inter alia materials science, opto‐electronics, pharmacy or catalysis. Concerning the latter one, a vast development has led to new or improved applications in both "conventional" organic chemistry (i. e., catalysis of functional‐group interconversions, CH‐activation or cross‐coupling reactions) as well as energy‐related applications (e. g., CO2 reduction, artificial photosynthesis, dye degradation). In this respect, not only homogeneous catalysts (i. e., molecular complexes) but also heterogeneous and recyclable ones have moved to the focus of interest. These heterogeneous structures include 1D metallopolymers, metal‐organic frameworks (MOFs), organic‐inorganic hybrids and bio‐inspired catalysts. We gave a first overview on this topic already in 2011; in here, the methods and implementations established within the last decade as well as relevant contributions from earlier works are presented and discussed. [ABSTRACT FROM AUTHOR]

A novel ternary heterojunction nanocatalyst, p-ZnIn 2 S 4 /rGO/n-g-C 3 N 4 , was synthesized as a low-cost, high-efficiency photoelectrocatalyst. A hybrid composite of p-type ZnIn 2 S 4 , n-type g-C 3 N 4 , and GO was formed at 80 °C by a simple hydrothermal method. When installed in a dark self-biased fuel cell with cathodic Pt nanocatalysts, the anodic p-ZnIn 2 S 4 /rGO/n-g-C 3 N 4 (83%) achieved higher triclosan (TCS) pollutant removal rate than anodic ZnIn 2 S 4 /g-C 3 N 4 (52.3%), ZnIn 2 S 4 (35%), and g-C 3 N 4 (18%) after 30 min. Moreover, the p-ZnIn 2 S 4 /rGO/n-g-C 3 N 4 not only extended the photo-response range but also accelerated the electron transfer and electron–hole separation in the absence of light or any external energy input. By comparing the different conditions in the fuel cell system, the dark condition was still comparable to the visible light and ultraviolet irradiation during the final monitoring time. scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM) were applied to characterize the morphology, composition, and structure of ZnIn 2 S 4 /g-C 3 N 4 , ZnIn 2 S 4 , and g-C 3 N 4. Furthermore, reactive oxygen species were formed via aeration and activation of molecular oxygen through interfacial electron transfer, and active species were detected via electron spin resonance spectrometer (ESR). Finally, TCS degradation mechanisms in the self-biased fuel cell were proposed. Image 1 [ABSTRACT FROM AUTHOR]

The combination of different semiconductors to form a heterojunction plays an important role for exploring new visible-light-driven electrocatalysts. Herein, a two-dimensional (2D) Bi 2 WO 6 /La 2 Ti 2 O 7 (LTO) heterojunction has been synthesized and to be as carrier of Pt nanoparticles. Subsequently, electrocatalytic activity and stability of the as-obtained Pt-Bi 2 WO 6 /LTO has been evaluated in methanol oxidation reaction (MOR) under the action of visible light and electricity. Results indicate that Pt-Bi 2 WO 6 /LTO sample displays excellent catalytic performance and stability with assistance from visible light. Under identical conditions, the current intensity of MOR on the Pt-Bi 2 WO 6 /LTO modified electrode is found to reach 1409 mA mg−1 Pt , which is 3.92 times higher than the measured Pt-Bi 2 WO 6 modified electrode (359.8 mA mg−1 Pt). In addition, the current density of MOR on Pt-Bi 2 WO 6 /LTO electrode decreases by 2.85% after scanning for 300 cycles. Furthermore, Pt-Bi 2 WO 6 /LTO is 6.99 times more resistant to poisoning than the Pt-Bi 2 WO 6 electrode determines by chronopotentiometry under visible light illumination. The presented results indicate that a Pt-Bi 2 WO 6 /LTO nanocomposite is a viable alternative photo-electric catalyst, providing a potential new basis for the future development of catalysts in fuel cell reactions. [ABSTRACT FROM AUTHOR]

BACKGROUND: Sustainable production of oxygen and hydrogen via catalyst‐aided water splitting utilizing solar energy has attracted increasing interest. The primary issue in this field is the development of earth‐abundant and active photoelectrocatalytic materials. Herein, a novel hierarchical g‐C3N4/g‐C3N4 metal‐free homojunction catalyst is synthesized through partial hydrolysis of melamine in alkali and subsequent thermal treatment. RESULTS: The hierarchical g‐C3N4/g‐C3N4 metal‐free homojunction composed of lamellas features large exposed surface area, abundant interface contact and more channels for mass transfer, making it highly effective for water splitting with a small overpotential of 500 mV at 10 mA cm−2 and low Tafel slope of 93.1 mV dec−1 for oxygen evolution reaction (OER) in 1.0 mol L−1 potassium hydroxide (KOH) solution, as well as 259 mV at 10 mA cm−2 and 109.33 mV dec−1 for hydrogen evolution reaction (HER) in 0.5 mol L−1 sulfuric acid (H2SO4) solution. Furthermore, the overpotential and Tafel slope further decrease to 383.4 mV and 69.52 mV dec−1 for OER, 150.1 mV and 67.93 mV dec−1 for HER upon visible light irradiation, demonstrating the exceptional photo‐responsive catalytic performance, which can be attributed to the direct Z‐scheme homojunction resulting in effective charge transfer and •OH and superoxide free radicals produced under visible light irradiation. CONCLUSION: This work provides a facile but effective approach for the construction of metal‐free OER/HER bifunctional catalyst with high photo‐responsive performance, achieving higher activity for catalyst‐assisted water splitting. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Currently, hydrogen generation via photocatalytic water splitting using semiconductors is regarded as a simple environmental solution to energy challenges. This paper discusses the effects of the doping of noble metals, Ir (3.0 at.%) and Ni (1.5–4.5 at.%), on the structure, morphology, optical properties, and photoelectrochemical performance of sol-gel-produced SnO2 thin films. The incorporation of Ir and Ni influences the position of the peaks and the lattice characteristics of the tetragonal polycrystalline SnO2 films. The films have a homogeneous, compact, and crack-free nanoparticulate morphology. As the doping level is increased, the grain size shrinks, and the films have a high proclivity for forming Sn–OH bonds. The optical bandgap of the un-doped film is 3.5 eV, which fluctuates depending on the doping elements and their ratios to 2.7 eV for the 3.0% Ni-doped SnO2:Ir Photoelectrochemical (PEC) electrode. This electrode produces the highest photocurrent density (Jph = 46.38 mA/cm2) and PEC hydrogen production rate (52.22 mmol h−1cm−2 at −1V), with an Incident-Photon-to-Current Efficiency (IPCE% )of 17.43% at 307 nm. The applied bias photon-to-current efficiency (ABPE) of this electrode is 1.038% at −0.839 V, with an offset of 0.391% at 0 V and 307 nm. These are the highest reported values for SnO2-based PEC catalysts. The electrolyte type influences the Jph values of photoelectrodes in the order Jph(HCl) > Jph(NaOH) > Jph(Na2SO4). After 12 runs of reusability at −1 V, the optimized photoelectrode shows high stability and retains about 94.95% of its initial PEC performance, with a corrosion rate of 5.46 nm/year. This research provides a novel doping technique for the development of a highly active SnO2-based photoelectrocatalyst for solar light-driven hydrogen fuel generation.

Polycyclic aromatic hydrocarbons (PAHs) are persistent environmental pollutants and the development of systems that transform or eliminate PAHs would be of great interest for both the human health and environmental protection. In this study, photoelectrocatalytic composite electrodes were successfully prepared for phenanthrene (PHE) degradation under low current density conditions. The electrodes were made of titanium dioxide (TiO2) and phosphomolybdic acid (PMo12) assembled through layer-by-layer to yield PMo12/CNTs/TiO2/Ti composites. The as-obtained electrodes were characterized by scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. Electrochemistry showed PMo12/CNTs/TiO2/Ti electrodes to possess high photoelectrochemical activities due to broadened absorption spectra and solar light utilization efficiencies. The photoelectrocatalytic degradation of PHE was evaluated at different light sources at current density of 50 µA cm-2. Under sunlight, PHE at concentrations around 1.5 mg L-1 were completely degraded within 60 min. The constant of zero-order kinetics for PHE degradation was estimated to 0.0227 mg L-1 min-1, and the reaction was identified as surface-controlled catalysis. A mechanism of charge separation was also proposed. Overall, these findings look promising for future catalysis associated with environmental remediation. [ABSTRACT FROM AUTHOR]

The nanosheets of Bi 2 MoO 6 were loaded to surface of TiO 2 NTs (grown on Ti mesh) via simple solvothermal method and the amount of Bi 2 MoO 6 nanosheets was adjusted by changing reaction intervals. The PEC removal efficiency of RhB, MO, MB and Cr (VI) achieved 75%, 100%, 100% and 100%. The type-II heterojunction mechanism was tentatively proposed. The fabrication of TiO 2 NTs/Bi 2 MoO 6 type-II heterojunction photocatalyst was carried out by a simple solvothermal method. Bi 2 MoO 6 nanoparticles with nanosheet microstructures were successfully loaded on TiO 2 NTs surface through the adjustment of reaction intervals. The heterojunction photocatalyst showed excellent organic dye and heavy metal ion removal performances, and nearly 100%, 75%, 100% and 100% of MO, RhB, MB and Cr (VI) were removed by simulative sunlight irradiation for 3 or 2 h, respectively. The outstanding photocatalyic performance was mainly due to the formation of type-II heterojunction between TiO 2 and Bi 2 MoO 6. The type-II heterojunction not only enhanced visible light response but also accelerated photogenerated charge carrier transfer and restrained the recombination of photogenerated electron-hole pairs with the assistance of internal electric field. [ABSTRACT FROM AUTHOR]

In this work, we study the effect of Cu2O film obtained from a fully reacted Cu seed layer as a photoelectrode in photoelectrochemical cells. The full reaction of the Cu layer shows an enhanced photocurrent density and improved efficiency in hydrogen evolution. The photocurrent density of textured Cu2O (0.58 mA cm−2 at 0 V vs. RHE), without an unreacted Cu layer is two times higher than films containing an unreacted Cu layer (0.29 mA cm−2 at 0 V vs. RHE), under AM 1.5 illumination (100 mW cm−2). The thickness of the unreacted Cu layer influences significantly the charge transfer process at the interface between the Cu2O and electrolyte. The enhanced photoelectrochemical performance of textured Cu2O is attributed to the reduced charge recombination resulting from a longer carrier lifetime in the Cu2O layer. Experimentally we confirmed that the unreacted Cu layer inhibits the photoelectrochemical performance of Cu2O‐based photocathodes. The elimination of the unreacted Cu layer leads to higher photocurrent density. [ABSTRACT FROM AUTHOR]

A novel 3D leaf-like Fe 2 O 3 -Bi 2 O 3 -Bi 2 S 3 photoelectrocatalyst was constructed through electrodeposition and hydrothermal reaction and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) and UV–Vis absorbance spectra. Results indicated the successful construction of 3D leaf-like Bi 2 O 3 -Bi 2 S 3 nanosheets covered Fe 2 O 3 nanoparticles, which could favor light refraction, improve light absorption, reduce charge transfer resistance, and facilitate the separation of photogenerated electron-hole pairs. The photocurrent density of Fe 2 O 3 -Bi 2 O 3 -Bi 2 S 3 was ca. 8 and 7 times higher than that of bare Fe 2 O 3 at 0.45 V vs Ag/AgCl under visible and UV–vis light irradiation, respectively. The Fe 2 O 3 -Bi 2 O 3 -Bi 2 S 3 film exhibited higher photoelectrocatalytic (PEC) performance on the degradation of refractory pollutants than Fe 2 O 3 and Fe 2 O 3 -Bi 2 O 3 films under visible irradiation. Effects of applied potential and trapping agents were studied. The main active species in PEC process was the h+, HO• and O 2 •-. A proposed mechanism of charge transfer in Fe 2 O 3 -Bi 2 O 3 -Bi 2 S 3 was discussed. This work provided a potential candidate material for PEC application in environmental remediation. [ABSTRACT FROM AUTHOR]

In an era of graphene-based nanomaterials as the most widely studied two-dimensional (2D) materials for enhanced performance of devices and systems in solar energy conversion applications, molybdenum disulfide (MoS2) stands out as a promising alternative 2D material with excellent properties. This review first examined various methods for MoS2 synthesis. It, then, summarized the unique structure and properties of MoS2 nanosheets. Finally, it presented the latest advances in the use of MoS2 nanosheets for important solar energy applications, including solar thermal water purification, photocatalytic process, and photoelectrocatalytic process. [ABSTRACT FROM AUTHOR]

[Display omitted] • The strategies for improving the PEC performance of carbon-based semiconductor photoelectrocatalysts are elaborated. • The latest applications of carbon-based semiconductor photoelectrocatalysts in organic pollutant removal are thoroughly summarized. • The mechanism of carbon-based materials improving the PEC efficiency and their roles in PEC systems are emphasized. • The profound insights into the future development of carbon-based semiconductor photoelectrocatalysts are proposed. Photoelectrocatalysis (PEC) technology has attracted broad interest due to its great application potential in pollutant removal and energy production. However, the high recombination of photogenerated electron-hole pairs, low utilization efficiency of solar energy, and limited reaction area are still the main obstacles that limit the practical applications of PEC. Carbon-based materials with unique and excellent properties are widely coupled with semiconductors to prepare composite photoelectrocatalysts to address the above problems. Carbon-based materials can serve as supporting materials, conductive substrates, electron transfer media, photosensitizers, and stabilizers to greatly improve the photoelectrocatalytic performance of semiconductors. Meanwhile, carbon-based materials can exert semiconductor properties to generate electron-hole pairs or construct heterojunctions with semiconductors to efficiently promote charge separation. In this review, a comprehensive summary is given to introduce synthetic methods and improvement strategies of carbon-based material/semiconductor composite photoelectrocatalysts, as well as their latest applications in the removal of organic pollutants. Especially, the roles of carbon-based materials in the PEC process are highlighted. Finally, current challenges and prospects are put forward. We do hope that this article can outline the recent advances and provide new insights for the future development of carbon-based semiconductor photoelectrocatalysts applied in water treatment. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) water splitting is a promising strategy to improve the efficiency of oxygen evolution reactions (OERs). However, the efficient adsorption of visible light as well as long-term stability of light-harvesting electrocatalysis is the crucial issue in PEC cells. Metal–organic framework (MOF)-derived bimetallic electrocatalysis with its superior performance has wide application prospects in OER and PEC applications. Herein, we have fabricated a nickel and iron bimetallic organic framework (FeNi-MOF) deposited on top of anodized TiO2 nanotube arrays (TNTA) for PEC and OER applications. The FeNi-MOF/TNTA was incorporated through the electrochemical deposition of Ni2+ and Fe3+ onto the surface of TNTA and then connected with organic ligands by the hydrothermal transformation. Therefore, FeNi-MOF/TNTA demonstrates abundant photoelectrocatalytic active sites that can enhance the photocurrent up to 1.91 mA/cm2 under 100 mW/cm2 and a negligible loss in activity after 180 min of photoreaction. The FeNi-MOF-doped photoanode shows predominant photoelectrochemical performance due to the boosted excellent light-harvesting ability, rapid photoresponse, and stimulated interfacial energy of charge separation under the UV-visible light irradiation conditions. The results of this study give deep insight into MOF-derived bimetallic nanomaterial synthesis for photoelectrochemical OER and provide guidance on future electrocatalysis design.

Abstract Anatase supported heterogeneous photocatalyst consisting of RuO 2 , MnO 2 and Co 3 O 4 (1:13:13 ratio) was synthesized by a precipitation method and tested for photoelectrocatalytic (PEC) oxidation of methanol in 0.1 M KOH under visible light irradiation. The as-prepared photocatalyst was characterized by FTIR, UV–vis, XRD, Raman spectroscopy, FESEM/EDX, TEM, BET, XPS and TPR. The PEC studies by cyclic voltammetry indicated that the oxidation of methanol to CO 2 and H 2 O upon exposure to visible light occurs between 400 and 800 nm. The smaller value of the charge transfer resistance (R ct) of the RuO 2 MnO 2 Co 3 O 4 supported anatase TiO 2 electrode indicates a faster rate of charge transfer at the electrode-electrolyte interface compared to the Pt/C catalyst, which could be promising for direct methanol fuel cell application. Graphical abstract Image 1 Highlights • TiO 2 bandgap reduced and visible light absorption improved by addition of RuO 2 MnO 2 Co 3 O 4. • Formations of composite oxides onto TiO 2 decrease the e−-h+ recombination rates. • RuO 2 MnO 2 Co 3 O 4 are effective for visible light harvesting and charge separation. • RuO 2 MnO 2 Co 3 O 4 supported on TiO 2 oxidizes 4M methanol. • RuO 2 MnO 2 Co 3 O 4 supported on TiO 2 is suggested as an alternate for Pt/C. [ABSTRACT FROM AUTHOR]

Abstract Designing of high-performance photoanodes is essential for efficient solar energy conversion in photoelectrochemical (PEC) water splitting. Herein, we report an effective approach to synthesize three dimensional (3D) mixed-metal organic framework-coated ZnO nanowires array (ZnNi MOF@ZnO) for the effective PEC performance. The ZnO nanowires act as photon absorber as well as rapid charge transporter; whilst the ZnNi MOF provides the active sites for PEC process by lowering the energy barrier of water oxidation and suppressing electron-hole recombination. The 3D nanostructure of ZnNi MOF@ZnO nanowires array provides intimate interfacial contact through covalent interactions between the ZnNi MOF and ZnO nanowires which facilitates the rapid charge transfer during photocatalytic oxygen evolution reactions. As a result, the ZnNi MOF@ZnO nanowires array exhibited excellent photoelectrochemical water oxidation with very low onset potential (0.31 V vs. RHE) and high photocurrent density (1.40 mA/cm2) as compared to the Zn MOF @ZnO and ZnO nanowires array. This facile strategy provides a promising direction towards high performance photoanode design for adequate solar energy conversion. Graphical abstract Image 1 Highlights • ZnNi MOF@ZnO is an efficient anode for photoelectrochemical OER. • ZnNi MOF@ZnO is synthesized via a facile two-steps hydrothermal method. • OER on ZnNi MOF@ZnO shows 0.31 V onset potential and 1.4 mA/cm2 photocurrent density. • Thin layer ZnNi MOF facilitates charge separation and transfer efficiency during OER. [ABSTRACT FROM AUTHOR]

The main aim of this study was to synthesize and characterise tungstate (WO 3 ) nanocomposites with its metal-based nanostructures, such as copper (II) tungstate (CuWO 4 ) and nickel tungsten oxide (NiWO 4 ), as visible-light active thin film photoanodes for solar-driven photoelectrochemical (PEC) water oxidation. FE-SEM and AFM results showed that the bare as-deposited WO 3 films were transformed into polycrystalline WO 3 structure with highly agglomerated surfaces and roughness during the annealing-induced crystallisation process. XRD results suggested that the bare as-deposited WO 3 films undergone phase transformation process from amorphous to the photoactive monoclinic-I (γ-WO 3 ) at 550 °C. XPS results indicated the existence of WO 4 2− , Ni 2+ and Cu 2+ ions at 35.58 eV, 856 eV and 932.4 eV, respectively. Through the formation of WO 3 nanocomposites, the energy band gap was effectively lowered from 2.7 eV (γ-WO 3 ) → 2.3 eV (γ-WO 3 /CuWO 4 ) → 2.1 eV (γ-WO 3 /NiWO 4 ) as estimated from the UV–Vis spectra. Finally, the corresponding photoactivity of WO 3 nanocomposites was estimated by measuring the photocurrent density and γ-WO 3 /NiWO 4 nanocomposite structure was found to give the highest photocurrent density of 400 μA/cm 2 at 1.5 V vs Ag/AgCl (4 M KCl). [ABSTRACT FROM AUTHOR]

Photoelectrocatalytic oxidation based on noble/semiconductor has been a renewed interest in the past decades. The lack of high-performance semiconductor support remains a challenge for the harvesting and conversion of solar energy. Here, we report the syntheses of two dimensional (2D) BiOBr nanosheets with the superiorities of suitable band gaps, nontoxic, corrosion resistant and so on. These features enable them unprecedented performance for acting as the visible-light-driven support towards alcohol oxidation. Firstly, the pure BiOBr nanosheet has negligible activity towards alcohol oxidation. After the deposition of Pt nanoparticles (NPs), the as-prepared Pt-BiOBr composites show superior electrocatalytic activities towards ethanol and methanol oxidation reaction under visible light irradiation, with the mass activities of 929.8 mA mg −1 Pt and 751.7 mA mg −1 Pt , 6.0 and 28.4-fold enhancements than those under dark condition, respectively. The great enhancement in the photoelectrocatalytic performances can be attributed to the unique 2D nanostructure, synergistic and photocatalytic effects. This work may pave up a new route for designing the desirable semiconductor supports for the decoration of the noble metal catalysts, showing significant promise for the application of fuel cells. [ABSTRACT FROM AUTHOR]

Producing clean fuel (O 2 and H 2 ) using semiconductors through solar driven water splitting process has been considered as a promising technology to mitigate the existing environmental issues. Unlike the conventional single photoabsorbers, heterostructured semiconductors exhibit the merits of improved solar light photon harvesting and rapid charge separation, which are anticipated to result in high quantum yield of solar fuel generation in photoelectrochemical (PEC) cells. In this report, we demonstrate the electrospun derived WO 3 backbone fibrous channel as heteropartner to the primary photoabsorber (Fe 2 O 3 and BiVO 4 ) for promoting the electron transport from charge injection point to charge collector as well as photoholes to the electrolyte. We examine structure, optical, photoelectrochemical and charge transfer property of Fe 2 O 3 /WO 3 and BiVO 4 /WO 3 electrodes. These results were compared with directly coated Fe 2 O 3 and BiVO 4 photoabsorber onto conducting substrate without WO 3 backbone. The optical results showed that the absorbance and visible light activity of Fe 2 O 3 and BiVO 4 is significantly improved by WO 3 backbone fibers due to high amount of photo absorber loading. In addition, one dimensional (1-D) WO 3 fibers beneficially enhance the optical path length to the photoanode through light scattering mechanism. The electrochemical impedance analysis exhibits WO 3 nanofiber backbone reduces charge transfer resistance at Fe 2 O 3 and BiVO 4 by rapid charge collection and charge separation compare to backbone-free Fe 2 O 3 and BiVO 4 . As a result, Fe 2 O 3 /WO 3 and BiVO 4 /WO 3 fibrous hetero interface structures showed fourfold higher photocurrent generation from PEC cell. [ABSTRACT FROM AUTHOR]

The main aim of this study was to prove the concept and elucidate the effect of a bilayer tungsten trioxide (WO 3 ) nanojunction with different crystal growth orientation for improved photoactivity under visible light irradiation. For the first time, the concept of a bilayer WO 3 nanojunction with different crystal growth orientation was demonstrated. A layer-by-layer assembly for the bilayer WO 3 nanojunction with the same monoclinic ɣ-WO 3 crystal structure, but with two different crystal growth orientation of {002} at 600 °C and {200} at 500 °C was synthesized via the controlled electrodeposition-annealing method. Photocurrent measurements showed that the individual photoactivity of WO 3 thin film with {002} crystal growth orientation was higher than that of WO 3 thin film with {200} crystal growth orientation, while the bilayer WO 3 nanojunction with different crystal growth orientation exhibited the highest photoactivity. To further characterise the bilayer WO 3 nanojunction, X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), high resolution-transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and photocurrent density measurements were performed. Based on the findings, a theoretical postulation model was proposed in explaining the transfer of photogenerated charge carriers in bilayer WO 3 nanojunction that leads to improved photoactivity under visible light irradiation. [ABSTRACT FROM AUTHOR]

Spherical silver nanoparticles (Ag–NPs) were grown on near spherical β-SiC to assess the photocatalytic and antibacterial performance in the perspective of the future development of Ag decorated SiC porous membrane for next generation water treatment. A classic hierarchical structure of Ag on SiC (Ag@SiC) particles was developed in the presence of different percentage of 1, 3, and 5 wt% Ag. These were evaluated for the photocatalytic (PC) degradation behavior of organic dyes and E.coli under irradiation of UV-light. The optimum 3 wt% Ag-decorated β-SiC photocatalyst enhances the rate of dye degradation in the presence of external potential of 3 V. Schottky barrier formation in the interface between Ag@SiC improves the charge separation and consequently enhances the efficiency of the degradation process. Strong antimicrobial effect is observed at lower potential that can be attributed to effective charge transfer by metallic silver thereby suppressing the probable recombination through active separation. The catalyst were found stable and analyzed in the perspective of reuse and reproducibility. Thus, nano Ag (3 wt%) @β-SiC is a prospective material for water treatment. [ABSTRACT FROM AUTHOR]

CdSe Quantum Dots (QDs) are promising photocatalyst in the visible region and oxide perovskites like LaNiO 3 (LNO) are one of the best materials for photoelectrochemical water splitting. In this work, we have successfully synthesized the LNO@CdSe hetero-junction by the impregnation method. Formation of LNO@CdSe hetero-junction was characterized by using physicochemical techniques such as XRD, UV-DRS, FE-SEM, XPS and HRTEM. These results confirmed the successful formation of the LNO@CdSe hetero-junction. Photoanodes were fabricated by the drop-casting method to perform their photoelectrochemical properties toward water splitting. LNO@CdSe hetero-junction exhibits photocurrent density with 1.11 mA/cm2 at 0.8 V vs. SCE, which is a 4.62-fold enhancement compared to bare LNO. The enhanced photoelectrochemical properties is due to the formation of hetero-junction with visible light absorbing CdSe QDs. Besides, LNO absorbs the light in the near infra-red region. Hence, the LNO@CdSe hereto-junction absorbs the light from the visible to near infra-red region. In addition to that, the band alignment of the hetero-junction is favourable for the transformation of photogenerated electrons from the conduction band of CdSe QDs to the conduction band of the LNO, which results in the lesser recombination of the electron/hole pairs. This work suggests, this material can be a potential candidate in near future for green hydrogen and oxygen production using solar energy. [Display omitted] • A novel strategy is proposed to developed LNO@CdSe hetero-junction for enhanced photoelectrochemical water splitting. • LNO@CdSe showed photocurrent density of 1.11 mA/cm2 at 0.8 V vs. SCE, which 4.62-fold enhancement as compared to bare LNO. • The enhancement of photo-current density due to the presence of CdSe QDs. • LNO@CdSe showed the good photo absorption and charge carrier properties under visible region. [ABSTRACT FROM AUTHOR]

p-type Cu-doped ZnO nanorods (Cu/ZnO NRs) were electrodeposited on F-doped tin oxide (FTO) substrates at low temperature and the effect of Cu doping on the structural, morphologic, conductivity, optical and photoelectrocatalytic properties of ZnO NRs were systematically investigated. XRD patterns shows all samples growth along c-axis perpendicular to the plane of the glass substrate and Cu 2+ ions substituted with Zn 2+ ions and did not changed the hexagonal wurtzite structure of the ZnO nanorods. SEM images shows pure and Cu-doped ZnO NRs vertically well–aligned throughout the substrate surface with a hexagonal shape which had an average diameter around 100–150 nm. UV–visible experiments show optical band gap of ZnO NRs decrease by Cu doping. Mott-Schottky analysis reveals that Cu doping induce p-type conductivity in ZnO NRs with high hole density. EIS and voltammetry analysis indicate that Cu doping effectively increased electron-hole separation under visible light and enhance photoelectrocatalytic property of ZnO NRs toward CO 2 reduction. [ABSTRACT FROM AUTHOR]

Two dimensional (2D) BiOI nanoplates were synthesized and used as support for the deposition of Pt nanoparticles. Owing to broad visible light absorption (up to 660 nm), the as-obtained Pt–BiOI electrode was used as effective photoelectrocatalyst in the application of catalytic ethanol oxidation in alkaline media under visible light irradiation. Compared to dark condition, the Pt–BiOI modified electrode displayed 3 times improved catalytic activity towards ethanol oxidation under visible light irradiation. The synergistic effect of electrocatalytic and photocatalytic, and the unique of 2D structures contribute to the improvement of catalytic activity. The mechanism of enhanced photoelectrocatalytic process is proposed. The present results suggest that 2D visible-light-activated BiOI can be served as promising support for the decoration of Pt and applied in the fields of photoelectrochemical and photo–assisted fuel cell applications [ABSTRACT FROM AUTHOR]

Realizing efficient charge separation and transfer is a key challenge for solar energy conversion. Here, we proposed the creation of an external electric field (EEF) by molecules interface engineering with silane grafting to form strong positive electricity on surface in semiconductor photocatalyst, driving charge separation and transfer in both bulk and surface. Forced by the EEF, WO 3 nanoplates anchored silane molecules (WO 3 -SiH 2 NH 2 ) for efficient photoelectrochemical (PEC) water oxidation shows 44.8% photocurrent enhancement. Interestingly, the photocurrent onset on WO 3 -SiH 2 NH 2 exhibited a 0.3 V negative shift from 0.5 to 0.2 V RHE compared with pure WO 3 caused by the change of band edge position. The strategy of creating EEF is proven effective using other semiconductors and opens up a potential application to construct numerous high performance photoelectrodes for water splitting. [ABSTRACT FROM AUTHOR]