Reduced graphene oxide/Cu<Subscript>2</Subscript>O nanostructure composite films as an effective and stable hydrogen evolution photocathode for water splitting

An efficient photocathode consisting of reduced graphene oxide/Cu₂O/Cu (rGO/Cu₂O/Cu) has been successfully prepared in this work via a facile two step method, consisting of chemical oxidation of a copper foil in alkaline solution using (NH₄)₂S₂O₈ as the oxidizing agent, dipping the prepared samples in graphene oxide (GO) solution and calcination at vacuum to form a rGO layer onto Cu₂O/Cu photocathode, which acts as a protective layer. The products were composed of a thin Cu₂O layer topped with a thin rGO film as the protective coating. The chemical composition and rGO amount in the composite materials were easily controlled by changing the immersion time to enhance PEC performance. UV–Vis spectroscopy, Raman spectroscopy, XRD, SEM, TEM and FTIR spectroscopy were used in the optical and morphological characterization of the graphene oxide and prepared photocathodes. Distinct patches of GO film are formed on the Cu(OH)₂ nanostructure surface, as shown by SEM results. Linear sweep voltammetry and chronoamperometry analysis have been applied in the photoelectrochemical characterizations in the dark and under illumination conditions. Photocurrent density provided by rGO/Cu₂O/Cu photocathode ??2.54 mA cm^??2 is three times greater than that of bare Cu₂O/Cu photocathode ??0.82 mA cm^??2 at 0 V vs. RHE under illumination. Low photostability of 42% is exhibited by bare Cu₂O/Cu photocathode after 200 s irradiation whereas rGO/Cu₂O/Cu photocathode shows approximately 98% of the initial photocurrent density. Therefore, a strategy has been developed in this work for the synthesis of this new photocathode using Cu₂O/Cu as an effective photocathode for photoelectrochemical (PEC) water splitting.     

In<Subscript>2</Subscript>S<Subscript>3</Subscript> nanoparticles dispersed on g-C<Subscript>3</Subscript>N<Subscript>4</Subscript> nanosheets: role of heterojunctions in photoinduced charge transfer and photoelectrochemical and photocatalytic performance

Fast recombination of photogenerated charge carriers is a major problem in the photoelectrochemical and photocatalytic processes. In this work, we report significantly improved PEC performance of a nanocomposite consists of In₂S₃ nanoparticles dispersed on g-C₃N₄ nanosheets synthesized by a simple and facile wet chemical route. The results of high-resolution TEM study show that the obtained In₂S₃ nanoparticles of size 10–20 nm exist in cubic phase and are uniformly dispersed on the surface of g-C₃N₄ nanosheets. The In₂S₃/g-C₃N₄ nanocomposite with 25 weight percentage of In₂S₃ exhibits 8.5 times higher photocurrent density than the single-phase g-C₃N₄ under visible light illumination. The enhanced photocurrent density exhibited by the In₂S₃/g-C₃N₄ nanocomposite is attributed to the efficient separation of photogenerated charge carriers. The charge transfer mechanism in In₂S₃/g-C₃N₄ heterojunction was studied by a series of experiments, such as electrochemical impedance spectroscopy, photoelectrochemical measurement and photoluminescence emission spectroscopy. The intimate interface promotes the charge transfer and inhibits the recombination rate of photogenerated electron–hole pairs, which significantly improves the photoelectrochemical performance. A detailed charge transfer mechanism is discussed based on the Mott–Schottky plot study. This heterojunction material is found to be an efficient photocatalyst for the degradation of both cationic rhodamine B dye and anionic methyl orange dye as the lifetime of photogenerated charge carriers is higher in the composite than in single-phase In₂S₃ and g-C₃N₄. A strong correlation between the photoelectrochemical and the photocatalytic performances is observed in this composite.     

A robust and self-assembled route to synthesis of CdZn(Se<Subscript>1−x</Subscript>Te<Subscript>x</Subscript>)<Subscript>2</Subscript> photoanodes as light harvesters for photoelectrochemical solar cells

This work reports on the development of CdZn(Se_1?xTe_x)₂ thin films utilized as the photoanode for photoelectrochemical cells (PECs). It was found that the incorporation of tellurium plays an important role in determining the optostructural, morphological, compositional and PEC performance of thin films. XRD measurements showed that the deposited thin films are in the mixed phases with a nanocrystalline nature. SEM images indicated that the surface morphology is favourable for effective light absorption in the solar spectrum. The EDS spectrum confirmed that thin film deposition occured in a stoichiometric manner. A detailed quantitative study was also executed using XPS and revealed the presence of Cd²⁺, Zn²⁺, Se^2? and Te^2? elements in the deposited thin film. Finally, the deposited thin films were tested for their photoelectrochemical (PEC) performance. The PEC study illustrated that CdZn(Se_1?xTe_x)₂ thin film showed the highest power conversion efficiency (η) of 1.13% among reported values.     

Spinel Structural Disorder Influences Solar‐Water‐Splitting Performance of ZnFe2O4 Nanorod Photoanodes

Zinc spinel ferrite, ZnFe₂O₄ (ZFO), is an emerging photoanode material for photoelectrochemical (PEC) solar fuel production. However, a lack of fundamental insight into the factors limiting the photocurrent has prevented substantial advance in its performance. Herein, it is found that ZFO nanorod array photoelectrodes with varying crystallinity exhibit vastly different PEC properties. Using a sacrificial hole scavenger (H₂O₂), spatially defined carrier generation, and electrochemical impedance spectroscopy, it is shown that ZFO with a relatively poor crystallinity but a higher spinel inversion degree (due to cation disorder) exhibits superior photogenerated charge separation efficiency and improved majority charge carrier transport compared to ZFO with higher crystallinity and a lower inversion degree. Conversely, the latter condition leads to better charge injection efficiency. Optimization of these factors, and the addition of a nickel–iron oxide cocatalyst overlayer, leads to a new benchmark solar photocurrent for ZFO of 1.0 mA cm^?2 at 1.23 V versus reversible hydrogen electrode (RHE) and 1.7 mA cm^?2 at 1.6 V versus RHE. Importantly, the observed correlation between the cation disorder and the PEC performance represents a new insight into the factors important to the PEC performance of the spinel ferrites and suggests a path to further improvement.     

Boosting Photo-Electro-Fenton Process Via Atomically Dispersed Iron Sites on Graphdiyne for InVitro Hydrogen Peroxide Detection

Hydrogen peroxide (H₂O₂) is essential in oxidative stress and signal regulation of organs of animal body. Realizing in vitro quantification of H₂O₂ released from organs is significant, but faces challenges due to short lifetime of H₂O₂ and complex bio-environment. Herein, rationally designed and constructed a photoelectrochemical (PEC) sensor for in vitro sensing of H₂O₂, in which atomically dispersed iron active sites (Hemin) modified graphdiyne (Fe-GDY) serves as photoelectrode and catalyzes photo-electro-Fenton process. Sensitivity of Fe-GDY electrode is enhanced 8 times under illumination compared with dark condition. The PEC H₂O₂ sensor under illumination delivers a wide linear range from 0.1 to 48 160 µm and a low detection limit of 33 nm , while demonstrating excellent selectivity and stability. The high performance of Fe-GDY is attributed to, first, energy levels matching of GDY and Hemin that effectively promotes the injection of photo-generated electrons from GDY to Fe³⁺ for reduced Fe²⁺, which facilitates the Fe³⁺/Fe²⁺ cycle. Second, the Fe²⁺ actively catalyzes H₂O₂ to OH^- through the Fenton process, thereby improving the sensitivity. The PEC sensor demonstrates in vitro quantification of H₂O₂ released from different organs, providing a promising approach for molecular sensing and disease diagnosis in organ levels.     

In<Subscript>2</Subscript>O<Subscript>3</Subscript>-decorated ordered mesoporous NiO for enhanced NO<Subscript>2</Subscript> sensing at room temperature

In this work, ordered mesoporous structures of In₂O₃-decorated NiO were prepared by a two-step process, comprising of the synthesis of ordered mesoporous NiO followed by injection of In³⁺ into their pores. The pore size distribution of the as prepared samples was between 4.1 and 21.1 nm. Furthermore, their sensing performances toward NO₂ were tested systematically. The results showed the highest response about 3 towards 15 ppm NO₂ sensing at room temperature for 5.0 at.% In₂O₃-decorated NiO compared to other decorated and pure samples. Moreover, the sensor displayed excellent selectivity towards NO₂ in the presence of other interfering gases, such as carbon monoxide, ammonia, ethanol, methanol, formaldehyde, toluene, acetone. The exceptional NO₂ sensing performance of the In₂O₃-decorated mesoporous NiO may be attributed to their high specific surface area and the formation of p–n junction with modified carrier concentration caused by In³⁺ doping. This method can act as an effective strategy for enhancement of gas-sensing properties of pure metal oxides.     

Structural,optical and magnetic properties of Cr doped In<Subscript>2</Subscript>O<Subscript>3</Subscript> powders and thin films

The (In_1?xCr_x)₂O₃ powders as well as thin films of x = 0.03, 0.05 and 0.07 were synthesized using a solid state reaction and an electron beam evaporation technique (on glass substrate), respectively. The influence of Cr doping concentration on structural, optical and magnetic properties of the In₂O₃ samples was systematically studied. The X-ray diffraction results confirmed that all the Cr doped In₂O₃ samples exist cubic structure of In₂O₃ without any secondary phases presence. The chemical composition analyses showed that all the Cr doped In₂O₃ compounds were nearly stoichiometric. The X-ray photoelectron spectroscopy analysis of the Cr doped In₂O₃ thin films showed an increase of oxygen vacancies with Cr concentration and the existence of Cr as Cr³⁺ state in the host In₂O₃ lattice. A small blue shift in the optical band gap was observed in the powder compounds, when the dopant concentration increased from x = 0.03 to x = 0.07. In thin films, the band gap found to increase from 3.63 to 3.74 eV, with an increase of Cr concentration. The magnetic measurements show that the undoped In₂O₃ bulk powder sample has the diamagnetic property at room temperature. And a trace of paramagnetism was observed in Cr doped In₂O₃ powders. However (In_1?xCr_x)₂O₃ thin films (x = 0.00, 0.03, 0.05 and 0.07) samples shows soft ferromagnetism. The observed ferromagnetism in thin films are attributed to oxygen vacancies created during film prepared in vacuum conditions. The ferromagnetic exchange interactions are established between metal cations via free electrons trapped in oxygen vacancies (F-centers).     

MOF-Derived In2O3/CuO p-n Heterojunction Photoanode Incorporating Graphene Nanoribbons for Solar Hydrogen Generation

Solar-driven photoelectrochemical (PEC) water splitting is a promising approach toward sustainable hydrogen (H₂) generation. However, the design and synthesis of efficient semiconductor photocatalysts via a facile method remains a significant challenge, especially p-n heterojunctions based on composite metal oxides. Herein, a MOF-on-MOF (metal-organic framework) template is employed as the precursor to synthesize In₂O₃/CuO p-n heterojunction composite. After incorporation of small amounts of graphene nanoribbons (GNRs), the optimized PEC devices exhibited a maximum current density of 1.51 mA cm⁻² (at 1.6 V vs RHE) under one sun illumination (AM 1.5G, 100 mW cm⁻²), which is approximately four times higher than that of the reference device based on only In₂O₃ photoanodes. The improvement in the performance of these hybrid anodes is attributed to the presence of a p-n heterojunction that enhances the separation efficiency of photogenerated electron-hole pairs and suppresses charge recombination, as well as the presence of GNRs that can increase the conductivity by offering better path for electron transport, thus reducing the charge transfer resistance. The proposed MOF-derived In₂O₃/CuO p-n heterojunction composite is used to demonstrate a high-performance PEC device for hydrogen generation.     

Poly(1,4‐Diethynylbenzene) Gradient Homojunction with Enhanced Charge Carrier Separation for Photoelectrochemical Water Reduction

As appealing photoelectrode materials for photoeletrochemical hydrogen evolution reaction (PEC HER), conjugated polymers still show poor PEC HER performance as a result of their serious recombination of photogenerated electrons and holes. Herein, a novel design of gradient homojunction is demonstrated by controlled copolymerization of 1,4‐diethynylbenzene (DEB) and 1,3,5‐triethynylbenzene (TEB). The as‐built gradient distribution of TEB monomer in poly(1,4‐diethynylbenzene) (pDEB) leads to continuous band bending engineering, which constitutes a gradient homojunction. Under AM 1.5G irradiation and in 0.1 m Na₂SO₄ aqueous solution, the as‐fabricated pDEB gradient homojunction exhibits a charge separation efficiency of 0.27% at 0.3 V versus reversible hydrogen electrode (RHE), which is 3.4 and 1.7 times higher than those for pure pDEB and the traditionally designed pDEB homojunction. As a result, the photocurrent of the pDEB gradient homojunction unprecedentedly reaches 55 µA cm^?2 at 0.3 V versus RHE, which is much higher than 19 µA cm^?2 for pure pDEB, 32 µA cm^?2 for the pDEB homojunction, and state‐of‐the‐art organic photocathodes, e.g., g‐C₃N₄ (≈1?32 µA cm^?2). This work opens up a new window for the design of gradient homojunctions and will advance the exploration of high‐performance organic photoelectrodes.     

Mixed Nb<Subscript>2</Subscript>O<Subscript>5</Subscript>:MoO<Subscript>3</Subscript> (95:5 and 85:15) thin films and their properties for electrochromic device applications

Nb₂O₅:MoO₃ (95:5 and 85:15) thin films were deposited onto glass and fluorine doped tin oxide coated glass substrates at 100 and 300 °C by RF magnetron sputtering technique. The physical and electrochromic properties of the films were studied. XRD result reveals that deposited films were amorphous. The XPS study confirms the compositional purity and the presence of Nb⁵⁺ and Mo⁶⁺ in the deposited film. Surface morphological study shows platelet like features of deposited film. The average transmittance of the film is varied between 91 and 85 %. Photoluminescence study exhibits three characteristic emission peaks and confirms the better optical quality of deposited film. Raman spectra show the LO–TO splitting of Nb–O stretching of the deposited film. Electrochromic behavior of the deposited films characterized by cyclic voltammetry using 0.5 M LiClO₄·PC and 0.5 M H₂SO₄ electrolyte solutions show all the films are having better reversibility and reproducibility in their electrochemical analysis.     

GaP/GaNP Heterojunctions for Efficient Solar‐Driven Water Oxidation

The growth and characterization of an n‐GaP/i‐GaNP/p⁺‐GaP thin film heterojunction synthesized using a gas‐source molecular beam epitaxy (MBE) method, and its application for efficient solar‐driven water oxidation is reported. The TiO₂/Ni passivated n‐GaP/i‐GaNP/p⁺‐GaP thin film heterojunction provides much higher photoanodic performance in 1 m KOH solution than the TiO₂/Ni‐coated n‐GaP substrate, leading to much lower onset potential and much higher photocurrent. There is a significant photoanodic potential shift of 764 mV at a photocurrent of 0.34 mA cm^?2, leading to an onset potential of ≈0.4 V versus reversible hydrogen electrode (RHE) at 0.34 mA cm^?2 for the heterojunction. The photocurrent at the water oxidation potential (1.23 V vs RHE) is 1.46 and 7.26 mA cm^?2 for the coated n‐GaP and n‐GaP/i‐GaNP/p⁺‐GaP photoanodes, respectively. The passivated heterojunction offers a maximum applied bias photon‐to‐current efficiency (ABPE) of 1.9% while the ABPE of the coated n‐GaP sample is almost zero. Furthermore, the coated n‐GaP/i‐GaNP/p⁺‐GaP heterojunction photoanode provides a broad absorption spectrum up to ≈620 nm with incident photon‐to‐current efficiencies (IPCEs) of over 40% from ≈400 to ≈560 nm. The high low‐bias performance and broad absorption of the wide‐bandgap GaP/GaNP heterojunctions render them as a promising photoanode material for tandem photoelectrochemical (PEC) cells to carry out overall solar water splitting.     

Electrochemically induced Ti<Superscript>3+</Superscript> self-doping of TiO<Subscript>2</Subscript> nanotube arrays for improved photoelectrochemical water splitting

We report a facile electrochemical reduction method to synthesize Ti³⁺-self-doped TiO₂ nanotube arrays (TNTs), where the effects of reduction duration and potential on the photoelectrochemical performance were systematically investigated. The X-ray photoelectron spectroscopy and electron paramagnetic resonance spectra confirmed the presence of Ti³⁺ in the TNTs. Under the optimum reduction condition, the Ti³⁺-self-doped TNTs exhibited remarkably enhanced photocurrent density and photoconversion efficiency, which were nearly 3.1 and 1.75 times that of pristine TNTs, respectively. The enhancement of PEC performance is due to the improved electrical conductivity, accelerated charge transfer rate at the TNTs/electrolyte interface, as well as the improved visible light response, which is elucidated by electrochemical impedance spectra, Mott–Schottky, and UV–Vis diffuse reflection spectra.     

Large enhancement of upconversion luminescence in Er<Superscript>3+</Superscript>/In<Superscript>3+</Superscript>:Ba<Subscript>0.85</Subscript>Ca<Subscript>0.15</Subscript>TiO<Subscript>3</Subscript> lead-free piezoelectric ceramics

A series of In³⁺-doped Ba_0.85Ca_0.15TiO₃:0.75%Er³⁺/xIn³⁺ (BCT:Er/xIn) lead-free piezoelectric ceramics with excellent upconversion luminescence were synthesized by the solid state reaction method. The effects of In³⁺ content on the crystal structure, ferroelectric, dielectric, piezoelectric, and upconversion luminescence properties were systematically studied. Under 980 nm excitation, a giant enhancement of the green emission (550 nm) by 10 times is achieved upon 2.5% mol In³⁺ doping, which is rarely observed in rare-earth ions-doped perovskite ferroelectric materials. The ultraviolet-visible-near infrared absorption measurements show that the In³⁺ doping may improve the dissolution of Er³⁺ ions and modify the isolate-/clustered-Er³⁺ ratio for x?≤?2.5%, resulting in the enhancement of the absorption cross-section, thereby contributing to the enhancement of green luminescence. Unfortunately, the In³⁺ doping suppresses the ferroelectric and piezoelectric properties of the BCT:Er/xIn ceramics. This problem can be resolved by adding a small amount (1 mol%) of Yb³⁺ to the BCT:Er/xIn ceramics to restore their good ferroelectric and piezoelectric properties. Such In³⁺ and rare-earth ions co-doped ceramics with greatly enhanced upconversion luminescence and good ferroelectricity and piezoelectricity may have potential applications in electro-optical devices.     

Fabrication of TiO<Subscript>x</Subscript>–Si photoanode and its energetic photoelectrochemical performance

Pristine Si is oxidized to insulative SiO₂ when it comes in contact with air and water. Covering it with a protection layer inhibits passivation of Si and significantly improves its photoelectrochemical performance. In this study, TiO_x with gradient change of oxygen stoichiometry ratio (TiO_x) was designed as a protection layer and fabricated via a chemical vapour deposition process in Ar flow under 400 °C for 1 min. The anaerobic atmosphere and short heating duration synergistically produced the ratio of O and Ti lower than two in the prepared film. XPS analysis suggested the existance of TiO₂ only at the surface of TiO_x film and Ti³⁺ and Ti²⁺ appeared successively with the increase of distance to the surface. The first advantage of lower-valence-state Ti and oxygen deficiency was to inhibit the oxidation of Si and to reduce electric resistance of the interface and the protection layer. The second advantage was to create a defect energy level under the conduction band of TiO₂ which provided the possibility for holes in the valence band of Si to be transferred to this defect level. This tunnel like transfer enhanced the photogenerated charge separation and redox ability of TiO_x–Si which brought a 3.25 folds enhancements in photocurrent density compared to that of stoichiometric TiO₂–Si at 0 V (SCE) under simulated sunlight. This study highly motivates further research on transparent and conductive protection layer of Si photoelectrode.     

3D Brochosomes‐Like TiO2/WO3/BiVO4 Arrays as Photoanode for Photoelectrochemical Hydrogen Production

An ideal photoelectrochemical (PEC) anode should process effective light absorption, charge transport, and separation efficiency. Here, a novel 3D brochosomes‐like TiO₂/WO₃/BiVO₄ array as an efficient photoanode by combining a colloid polystyrene sphere template and electrochemical deposition routes for PEC hydrogen generation is reported. The as‐fabricated 3D TiO₂/WO₃/BiVO₄ brochosomes photoanode yields excellent PEC performance with photocurrent densities of ≈3.13 and ≈4.27 mA cm^?2 with FeOOH/NiOOH catalyst, respectively, measured in 0.5 m Na₂SO₄ solution with 0.1 m Na₂SO₃ at 1.23 V versus reversible hydrogen electrode (RHE) under simulated AM1.5 light illumination, which is ≈6 times the reference sample of a planar WO₃/BiVO₄ film electrode. The significantly improved performance could be benefited from the ordered hollow porous structure that provides enhanced light absorption and efficient charge transport as well as improved charge separation efficiency by WO₃/BiVO₄ “host–guest” heterojunctions.     

Hierarchical CdS Nanorod@SnO2 Nanobowl Arrays for Efficient and Stable Photoelectrochemical Hydrogen Generation

An efficient photoanode based on CdS nanorod@SnO₂ nanobowl (CdS NR@SnO₂ NB) arrays is designed and fabricated by the preparation of SnO₂ nanobowl arrays via nanosphere lithography followed by hydrothermal growth of CdS nanorods on the inner surface of the SnO₂ nanobowls. A photoelectrochemical (PEC) device constructed by using this hierarchical CdS NR@SnO₂ NB photoanode presents significantly enhanced performance with a photocurrent density of 3.8 mA cm^?2 at 1.23 V versus a reversible hydrogen electrode (RHE) under AM1.5G solar light irradiation, which is about 2.5 times higher than that of CdS nanorod arrays. After coating with a thin layer of SiO₂, the photostability of the CdS NR@SnO₂ NB arrays is greatly enhanced, resulting in a stable photoanode with a photocurrent density of 3.0 mA cm^?2 retained at 1.23 V versus the RHE. The much improved performance of the CdS NR@SnO₂ NB arrays toward PEC hydrogen generation can be ascribed to enlarged surface area arising from the hierarchical nanostructures, improved light harvesting owing to the NR@NB architecture containing multiple scattering centers, and enhanced charge separation/collection efficiency due to the favorable CdS–SnO₂ heterojunction.     

Photochemical properties of SnO<Subscript>2</Subscript> nanorods arrays grown on nanoporous stainless steel

The synthesis and characterization of SnO₂ nanomaterials have been extensively studied as photoelectrodes for the potential applications in optoelectronic devices. In this work, SnO₂ nanorods arrays have been synthesized by hydrothermal method on the nanoporous surface of the anodized stainless steel. The prepared SnO₂ nanorods of 1.3–1.4 µm in length and 250–350 nm in width, were uniformly distributed on the anodized stainless steel. This one-dimensional SnO₂ nanostructure directly fabricated on the substrate provides an electron transfer pathway and a Schottky-type contact, resulting in improved photocatalytic and photoelectrochemical performance. The SnO₂ nanorods arrays exhibit fast response towards H₂O₂ determination, producing a linear range from 100 to 3000 μM with a correlation coefficient of 0.984 and a sensitivity of 0.66 μA cm^?2 mM^?1. The results indicate the potential applications of SnO₂ nanorods arrays as the non-enzymatic H₂O₂ sensor.     

Rietveld analysis of CaCu<Subscript>3</Subscript>Ti<Subscript>4</Subscript>O<Subscript>12</Subscript> thin films obtained by RF-sputtering

Calcium copper titanate, CaCu₃Ti₄O₁₂, CCTO, thin films with polycrystalline nature have been deposited by RF sputtering on Pt/Ti/SiO₂/Si (100) substrates at a room temperature followed by annealing at 600 °C for 2 h in a conventional furnace. The crystalline structure and the surface morphology of the films were markedly affected by the growth conditions. Rietveld analysis reveal a CCTO film with 100 % pure perovskite belonging to a space group Im3 and pseudo-cubic structure. The XPS spectroscopy reveal that the in a reducing N₂ atmosphere a lower Cu/Ca and Ti/Ca ratio were detected, while the O₂ treatment led to an excess of Cu, due to Cu segregation of the surface forming copper oxide crystals. The film present frequency -independent dielectric properties in the temperature range evaluated, which is similar to those properties obtained in single-crystal or epitaxial thin films. The room temperature dielectric constant of the 600-nm-thick CCTO films annealed at 600 °C at 1 kHz was found to be 70. The leakage current of the MFS capacitor structure was governed by the Schottky barrier conduction mechanism and the leakage current density was lower than 10^?7 A/cm² at a 1.0 V. The current–voltage measurements on MFS capacitors established good switching characteristics.     

Facile fabrication of three-dimensional interconnected nanoporous N-TiO2 for efficient photoelectrochemical water splitting

Three-dimensional (3D) interconnected porous architectures are expected to perform well in photoelectrochemical (PEC) water splitting due to their high specific surface area as well as favourable porous properties and interconnections. In this work, we demonstrated the facile fabrication of 3D interconnected nanoporous N-doped TiO₂ (N-TiO₂ network) by annealing the anodized 3D interconnected nanoporous TiO₂ (TiO₂ network) in ammonia atmosphere. The obtained N-TiO₂ network exhibited broadened light absorption, and abundant, interconnected pores for improving charge separation, which was supported by the reduced charge transfer resistance. With these merits, a remarkably high photocurrent density at 1.23 V vs. reversible hydrogen electrode (RHE) was realized for the N-TiO₂ network without any co-catalysts or sacrificial reagents, and the photostability can be assured after long term illumination. In view of its simplicity and efficiency, this structure promises for perspective PEC applications.     

Highly Transparent and Conductive Zn<Subscript>0.86</Subscript>Cd<Subscript>0.11</Subscript>In<Subscript>0.03</Subscript>O Thin Film Prepared by Pulsed Laser Deposition

Zn_0.86Cd_0.11In_0.03O alloy semiconductor film was deposited on quartz substrate by pulsed laser deposition technique. Cd is used to change the optical band gap and In is used to increase the carrier concentration of the ZnO film. XRD studies confirm that the structure of Zn_0.86Cd_0.11In_0.03O is hexagonal wurtzite structure without CdO phase appeared. FE-SEM shows that the grain size of Zn_0.86Cd_0.11In_0.03O film is smaller than that of ZnO. These films are highly transparent (∼85%) in visible region. Most importantly, the electrical properties of Zn_0.86Cd_0.11In_0.03O film highly improved with In doped. It has low resistivity (4.42×10⁻³ Ω cm) and high carrier concentration (5.50×10¹⁹ cm⁻³) that enable this film a promising candidate for window layer in solar cells and other possible optoelectronic applications.