In-situ growth of N–TiO2 on delaminated N–Ti3C2 with highly strengthened photocatalytic activity

Herein, a collection of N–TiO₂/delaminated N–Ti₃C₂ (NTTx) composites is designed and synthesized by one-step calcination of NH₄Cl–Ti₃C₂ precursors. The thermal decomposition of NH₄Cl not only serves as the gas template to make the delamination of Ti₃C₂, but also acts as N source to for doping. As expected, the N–TiO₂ nanoparticles uniformly anchor on the surface and interlayer of Ti₃C₂ nanosheets with intimate contact. Both the photocatalytic degradation rate of Rh–B and photocatalytic nitrogen fixation experiments of NTT2 composites show higher performance than that of pure P25 and NTT0 under visible light irradiation. The strengthened photocatalytic activity is due to the decrease of band gap by N doping in TiO₂ and excellent electrical conductivity of N–Ti₃C₂, which leads to enhanced light response and photogenerated electron-hole separation, respectively. This study develops a new strategy to design efficient photocatalysts for degradation of contaminants and fixation of nitrogen.     

B–N co-doped black TiO2 synthesized via magnesiothermic reduction for enhanced photocatalytic hydrogen production

In this work, B–N co-doped TiO₂ has been synthesized by a facile fast sol-gel method, and then, a controlled magnesiothermic reduction has been developed to synthesize B–N co-doped black TiO₂ under a N₂ atmosphere and at 580 °C followed by acid treatment. The prepared black TiO₂ samples were characterized by X-ray diffraction, high resolution transmission electron microscopy, Raman spectrameter, photoluminescence emission spectra, X-ray photoelectron spectroscopy, and ultraviolet–visible diffuse reflectance spectra. It shows that the prepared samples possess a unique crystalline core-amorphous shell structure composed of disordered surface and oxygen vacancies, and exhibit enhanced photocatalytic activity in hydrogen production in the methanol-water system in the presence of Pt as a co-catalyst. Under the full solar wavelength range of light, the maximum hydrogen production rate of the B–N co-doped black TiO₂ is 18.8 mmol h⁻¹ g⁻¹, which is almost 4 times higher than that of pure TiO₂.     

CdO–CdS nanocomposites with enhanced photocatalytic activity for hydrogen generation from water

Nanocomposites of CdO–CdS have been prepared in ethylene glycol water mixture followed by heating at 300 °C. TEM and XRD studies confirmed the atomic scale mixing of CdO and CdS nanoparticles, leading to the formation of CdSO₃ phase at the interfacial region between CdO and CdS. Photocatalytic studies for hydrogen generation from water show an enhanced activity for CdO–CdS composites compared to individual components namely CdO or CdS nanoparticles. Based on optical absorption, surface area measurements, steady state and time resolved fluorescence studies, it is established that, enhanced absorption in the visible region, higher surface area and increase in lifetime of the charge carriers are responsible for the observed increase in hydrogen yield from water when composite sample was used as the photocatalyst compared to individual components. The composite sample when combined with Pt as co-catalyst exhibit a large increase in the photocatalytic activity.     

Composition dependent activity of Fe1−xPtx decorated ZnCdS nanocrystals for photocatalytic hydrogen evolution

In this work, ZnCdS nanoparticles (NPs) were decorated with FePt alloy, forming nanocomposites via ethylene glycol reduction method. The photocatalytic H₂ production of the Fe_1?xPt_x–ZnCdS NPs was studied by changing the composition and weight percentage of Fe_1?xPt_x alloy in the nanocomposites under visible light (λ ≥ 420 nm) irradiation. The results showed that the hydrogen production rate of Fe_1?xPt_x–ZnCdS NPs had a significant enhancement over the pure ZnCdS (740 μmol g^?1 h^?1). The activity of the nanocomposites was dependent on the composition of Fe_1?xPt_x alloy and the highest hydrogen production rate of 2265 μmol g^?1 h^?1 was achieved by the 0.5 wt% Fe_0.3Pt_0.7–ZnCdS nanocomposites, which was even better than that of 0.5 wt% Pt–ZnCdS (1626 μmol g^?1 h^?1) under the same condition. This study highlights the significance of Pt base alloys as new cocatalysts for the development of novel composite photocatalysts.     

Facile in-situ synthesis of α-NiS/CdS p-n junction with enhanced photocatalytic H2 production activity

Constructing active sites on photocatalysts is one of the most effective approaches for promoting photocatalytic H₂ production activity. In this paper, a p-type semiconductor α-NiS is in-situ grown on an n-type semiconductor CdS by a simple solid state method, which results in a strong interfacial contact between α-NiS and CdS. Benefitting from the built-in electric field caused by a p-n junction, the photoinduced electrons of CdS and holes of α-NiS migrate to their interface and recombine rapidly, which results in the formation of a Z system. The more negative CB potential of α-NiS/CdS possesses stronger ability to reduce H⁺ to H₂, thereby exhibiting higher photocatalytic H₂ evolution activity. Furthermore, the strong interface contact is beneficial to the charge migration and promotes the charge separation efficiency. The H₂ evolution rate of 1.0% α-NiS/CdS reaches 9.8 mmol h^?1 g^?1, corresponding to an AQY of 65.7% at λ = 420 nm.     

Fabricating NixCo1−xO@C cocatalysts sensitized by CdS through electrostatic interaction for efficient photocatalytic H2 evolution

Exploiting efficient and stable noble metal-free hydrogen evolution catalysts for water splitting is of great importance. In this work, Ni_xCo_1-xO@C/CdS hybrid is successfully fabricated through an electrostatic interaction of oppositely charged nanoparticles on their surfaces. The resulting Ni_xCo_1-xO@C nanoboxes cocatalysts which were derived from NiCo-LDH@ZIF-67 with Ni–Co layered double hydroxides (LDH) decorated with ZIF-67 precursor exhibited improved hydrogen production rate compared with bare CdS semiconductor from 0.7 mmol g⁻¹ h⁻¹ to 56 mmol g⁻¹ h⁻¹. It is demonstrated that the electrostatic interaction between the two surface charged nanoparticles of Ni_xCo_1-xO@C and CdS play an important role in migrating and separating of photogenerated charge carriers. The synthesized Ni_xCo_1-xO@C as excellent candidates for cost-effective cocatalysts is aimed to substitute for noble metals in photocatalytic H₂ evolution.     

Insight into Ni/Ce1−xZrxO2−δ support interplay for enhanced methane steam reforming

Nickel catalysts supported in zirconium-doped ceria were optimized for methane steam reforming (MSR) at severe reaction conditions, i.e. low temperature and stoichometric water/methane feed ratio. The solids prepared were characterized by various techniques (BET, XRD, H₂-chemisorption, OSC, H₂-TPR, Raman and XPS), allowing a deeper understanding of the nickel-ceria based support interplay.     

Charge transfer processes involved in photocatalytic hydrogen production over CuO/ZrO2–TiO2 materials

Co-catalysts are widely employed to boost the photocatalytic hydrogen production; particularly, CuO has shown a remarkable improvement in the reaction rate. However, the impact of CuO on the charge transfer process during photocatalytic water reduction has been barely investigated. In this work, ZrO₂–TiO₂ (ZT) heterojunctions (5 mol% ZrO₂) have been obtained by means of the sol–gel method. Subsequently, copper nitrate impregnations are prepared by an incipient wetness impregnation method to get 0.5, 1, 3 and 5 wt% CuO loadings. A maximum in the photocatalytic activity is observed for the material containing 1 wt% CuO, followed by a drastic drop in the hydrogen generation rate. Electrochemical characterization shows that the charge-transfer resistance controls the photocatalytic experiments together with the additional interfacial resistance. The maximum photocatalytic activity is then given by a compromise between these two parameters. A further increase of the additional resistance, directly proportional to the CuO loading, reduces drastically the photocatalytic behavior most likely due to the electron trapping at the ZT–CuO interface.     

K–I co-doped crystalline carbon nitride with outstanding visible light photocatalytic activity for H2 evolution

Heteroatomic doping is an effective way to optimize the electronic structure of carbon nitride to boost photocatalytic performance. However, the extra introduced defects could result in the decrease of its crystallinity. In this work, crystalline K–I co-doped carbon nitride (K–I–CCN) was simply synthesized from molten salt ionthermal post-calcination in nitrogen atmosphere. Structure characterization results indicate that compared to K–CCN synthesized from conventional molten salt heat treatment in air, nitrogen heating atmosphere is more conductive for the formation of homogeneous pore structure of the catalyst, which has larger surface area and pore volume, while could repairing some defects and resulting in better polymerization crystallization. In addition, except the implanting of K, I doping is still retained after nitrogen heat treatment, thus forming K–I co-doping structure. Due to the positive charge effect of K–I co-doping, K–I–CCN has a narrower band gap, higher surface charge density and stronger charge transport, so it performs significantly enhanced photocatalytic H₂ evolution activity from water splitting.     

Comparing photocatalytic activity consisting of Sb2S3 and Ag2S on the TiO2–SiO2/TiO2 nanotube arrays-support for improved visible-light-induced photocatalytic degradation of a binary mixture of basic blue 41 and basic red 46 dyes

In the present study, a TiO₂ nanotube (TNAs) supported Sb₂S₃–TiO₂–SiO₂ (STS/TNAs), and Ag₂S–TiO₂–SiO₂ (ATS/TNAs) hybrid novel photocatalysts were prepared and characterized by XRD, FT-IR, SEM-EDX, X-ray mapping and, DRS. EIS was employed, and an equivalent circuit model is proposed. Flat-band potential and free carrier concentration were determined by Mott–Schottky plots. The obtained catalysts were used in the photodegradation of a binary mixture of Basic Blue 41 (BB41) and Basic Red 46 (BR46) dyes. Compared with ATS/TNAs, STS/TNAs photocatalyst showed the highest apparent rate constant for BB41 dye, about two times higher, and BR41 dye more than 1.5 times. EIS results agreed with the photodegradation results, so the STS/TNAs system with higher charge transfer ability than the ATS/TNAs system showed the best photodegradation activity. The optimization effect of the amount of Sb₂S₃, TiO₂, and SiO₂ doped on the TNAs on the photocatalytic activity of the STS/TNAs was done using a central composite rotatable design (CCRD) based response surface methodology (RSM). Results have shown catalyst containing 12.2% Sb₂S₃ and 27.1% SiO₂/TNAs (S₃TS₃/TNAs) the best photodegradation activity was obtained. The GC-Mass analysis was done to detect the degradation intermediates formed during the photodegradation process.     

Wavelength-dependent photoactivity of ZnxCd1−xS and ZnCo2O4/ZnxCd1−xS for H2 and H2O2 production

Zinc cadmium sulfide (Zn_xCd_1?xS) is a good photocatalyst for hydrogen evolution reaction (HER), but an optimum x (x_m) at which a maximum HER rate is reached varies from one report to another. In this work, we examine the effect of light wavelength, not only for the HER to H₂ in the presence of Na₂S and Na₂SO₃, but also for oxygen reduction reaction (ORR) without addition of any sacrifices. For the HER under a 365 and 420 nm LED lamp, the x_m were 0.9 and 0.7, respectively. For the HER under a 330 and 395–515 nm cut-off xenon lamp, the x_m were 0.7 and 0.5, respectively. For the ORR under a 420 nm cut-off halogen lamp, a maximum production of H₂O₂ was observed at x = 0.3. Furthermore, after 4% ZnCo₂O₄ loading, Zn_xCd_1?xS had an increased activity and stability, either for the HER or for the ORR. Through a (photo)electrochemical measurement, it is proposed that the photocatalytic activity of Zn_xCd_1?xS is determined by its light absorptivity and electron reactivity. The improved performance of n-type Zn_xCd_1?xS by p-type ZnCo₂O₄ is due to formation of a p-n junction, promoting the HER (ORR) on Zn_xCd_1?xS, and the sulfide (water) oxidation on ZnCo₂O₄. This work highlights that Zn_xCd_1-xS is a promising photocatalyst for H₂ and H₂O₂ production, respectively.     

H2 production of (CdS–ZnS)–TiO2 supported photocatalytic system

Mixed semiconductor (CdS–ZnS)–TiO₂(1 : 1 : 1) mixture system over different supports like MgO, CaO, γ-Al₂O₃, SiO₂ and modified MgO and CaO, have been prepared, characterized and tested for H₂ production in a S²⁻⧸SO²⁻₃ mixture solution. (CdS–ZnS)–TiO₂(D) over MgO support wherein the TiO₂ taken is from Degussa (D) sample gives 206.7 μmol⧸h of H₂ production and this catalyst sustain the H₂ production rate for longer durations. Dopants like Li₂O, Cs₂O or K₂O make MgO and CaO supports act like super basic oxide when they are doped and in turn increase the photocatalytic activity. The (CdS–ZnS)–TiO₂(I) system wherein the TiO₂ taken from Titanium Isopropoxide, supported on 20 wt% Li₂O doped CaO is found to give 209.8 μmol⧸h rate of H₂ production. Characterization studies like UV-Visible spectra, X-ray Diffraction spectra and Scanning Electron Microscope photographs were taken for all the catalysts and the data generated over these samples is evaluated. A scheme of H₂S photocatalytic decomposition of ZnCdS–TiO₂(D⧸I) over different supports in the presence of S²⁻⧸SO²⁻₃ substrate, is proposed indicating the formation of thiosulfate cycle at this heterojunction. © 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.     

Enhancing the photocatalytic activity of Cd–ZnS(EN)0.5 hybrid sheets for the H2 production

Ultrathin sheets of ZnS(EN)_0.5 modified with Cd²⁺ ions were prepared by chemical precipitation in a mixture of butanol-ethylenediamine-water solution. The Cd²⁺ content was varied from 0.1 to 0.6 M ratio and its influence in the physicochemical properties of the formed Cd–ZnS(EN)_0.5 hybrid compounds was investigated by diverse techniques: X-ray Diffraction, Thermogravimetric, Textural analysis, Infrared, Diffuse Reflectance and X-ray Photoelectron Spectroscopies, Scanning Electron and High-Resolution Transmission Electron Microscopy. The photocatalytic H₂ production of the unmodified ZnS(EN)_0.5 hybrid was tested using hydrazine, ethanol, and methanol as sacrificial electron donors reagents (SEDr), presenting an H₂ evolution rate of 2.4, 21 and 23 μmolh⁻¹, respectively. The results showed that the orthorhombic ZnS(EN)_0.5 structure was stable but suffer exfoliation of the lamellar structure during the photocatalytic cycles in methanol-water solution under UV irradiation. The doped Cd–ZnS(EN)_0.5 hybrid presented an enhanced H₂ production rate (32 μmolh⁻¹) for low Cd²⁺ doping, showing only minor exfoliation of the lamellar structure and stability of the orthorhombic structure, preserving the high photoactivity after 6 cycles of irradiation.     

One-pot synthesis of Cu–TiO2/CuO nanocomposite: Application to photocatalysis for enhanced H2 production,dye degradation & detoxification of Cr (VI)

Photocatalytic hydrogen production under the visible spectrum of solar light is an important topic of research. To achieve the targeted visible light hydrogen production and improve the charge carrier utilization, bandgap engineering and surface modification of the photocatalyst plays a vital role. Present work reports the one-pot synthesis of Cu–TiO₂/CuO nanocomposite photocatalyst using green surfactant -aided -ultrasonication method. The materials characterization data reveals the TiO₂ particle size of 20–25 nm and the existence of copper in the lattice as well as in the surface of anatase TiO₂. This is expected to facilitate better optical and surface properties. The optimized photocatalyst shows enhanced H₂ production rate of 10,453 μmol h⁻¹ g⁻¹ of the catalyst which is 21 fold higher than pure TiO₂ nanoparticles. The photocatalyst was tested for degradation of methylene blue dye (90% in 4 h) in aqueous solution and photocatalytic reduction of toxic Cr⁶⁺ ions (55% in 4 h) in aqueous solution. A plausible mechanistic pathway is also proposed.     

Surface defect and rational design of TiO2−x nanobelts/ g-C3N4 nanosheets/ CdS quantum dots hierarchical structure for enhanced visible-light-driven photocatalysis

TiO_2-x/g-C₃N₄/CdS ternary heterojunctions are fabricated through thermal polymerization-chemical bath deposition combined with in-situ solid-state chemical reduction approach. The prepared materials are characterized by X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption, and X-ray photoelectron spectroscopy. The results show that the ternary heterojunctions are formed successfully and CdS quantum dots (QDs) and TiO₂ are anchored on surface of g-C₃N₄ nanosheets simultaneously. The visible-light-driven photocatalytic degradation ratio of Bisphenol A and hydrogen production rate are up to 95% and ∼254.8 μmol h⁻¹, respectively, which are several times higher than that of pristine TiO₂. The excellent visible-light-driven photocatalytic activity can be ascribed to the synergistic effect of TiO_2−x, g-C₃N₄ and CdS QDs which extend the photoresponse to visible light region and favor the spatial separation of photogenerated charge carriers.     

Insight into NiCo-based nanosheets modified MnS/Mn0·2Cd0·8S hybrids for enhanced visible-light photocatalytic H2 evolution

Bimetallic compounds nanocrystals exhibited great potential in catalysis due to the synergistic effects and encouraging performance. Herein, a series of NiCo-based nanosheets, including NiCo LDH/NiCo(OH)₂, NiCo, and NiCo₂O₄, have been developed to modify MnS/Mn_0·2Cd_0·8S (MMCS) nanoparticles for photocatalytic H₂ production under visible light (λ > 420 nm). The two-dimensional (2D) NiCo₂O₄ and NiCo were derived from the oxidation and reduction process of the as-prepared NiCo LDH/NiCo(OH)₂ nanosheets, respectively. MMCS nanoparticles were prepared using a one-pot solvothermal method and then integrated into three different NiCo-based nanosheets through a simple hybridization approach. Compared to pure MMCS, the resultant NiCo-based nanosheets/MMCS hybrids show dramatically improved visible-light photocatalytic activities. Moreover, among the three types of composites, NiCo₂O₄-MMCS (7%NiCo₂O₄-MMCS) displays the highest H₂ production rate of 3.31 mmol g^?1 h^?1 with the apparent quantum efficiency of 6.42% at 420 nm, approximately 22 and 5 times that of pure MMCS (0.15 mmol g^?1 h^?1) and Pt/MMCS (0.67 mmol g^?1 h^?1), respectively. The remarkably enhanced photocatalytic activities of the NiCo LDH/NiCo(OH)₂-MMCS, NiCo-MMCS, and NiCo₂O₄-MMCS are mainly ascribed to the formed type-II, Schottky, and p-n heterojunctions, respectively, which efficiently boost photogenerated charge carrier separation and migration. In this paper, we intensively investigate the roles of three different NiCo-based nanosheets in the Mn_xCd_1-xS-based system. This work provides an effective strategy to design and construct the innovative 2D bimetallic compounds-based catalysts for high-efficiency photocatalytic H₂ production.     

Fabrication and band structure of Ag3PO4–TiO2 heterojunction with enhanced photocatalytic hydrogen evolution

Ag₃PO₄ was deposited on TiO₂ by in-situ precipitation to fabricate Ag₃PO₄–TiO₂ heterojunction with different ratios of Ag₃PO₄. The electronic band structures of TiO₂ and Ag₃PO₄ were determined by means of ultraviolet photoelectron spectroscopy and UV–visible spectrometry. The Fermi levels of TiO₂ and Ag₃PO₄ were calculated to be −5.09 eV and −5.95 eV, respectively, and accordingly the energy band diagrams were constructed. The hydrogen production rates of bare TiO₂ and Ag₃PO₄–TiO₂ heterojunctions were measured under 300 W Xe lamp with a solar filter (AM 1.5). The heterojunction formed with 12 wt% Ag₃PO₄ showed the highest hydrogen evolution rate (44.5 μmol g⁻¹h⁻¹) which is 5.7 times higher than that of TiO₂. When Au nanoparticles were deposited on this heterojunction, it resulted in 10.2 times (453.0 μmol g⁻¹h⁻¹) further improvement of hydrogen generation. The hydrogen evolution performance is consistent with the result of photoluminescence analysis.     

Decoration of Pt on the metal free RGO-TiO2 composite photocatalyst for the enhanced photocatalytic hydrogen evolution and photocatalytic degradation of pharmaceutical pollutant β blocker

Easy synthesis of graphene based composite photocatalyst with the incorporation of minimal quantity of noble metals for the enhanced photocatalytic hydrogen evolution as well as photocatalytic degradation and mineralization of recalcitrant pollutants under solar irradiation is an urgent requirement from the clean energy and environment point of view all over the globe. Herein, we demonstrate the decoration of Pt by photodeposition method on the hydrothermally synthesized RGO-TiO₂ nanocomposite. The various photocatalysts synthesized were successfully characterized by XRD, FTIR, Raman, UV–visible absorption spectra, XPS, SEM and TEM techniques. The well characterized photocatalysts were further investigated for the photocatalytic hydrogen evolution studies of methanol water mixtures under UV as well as simulated solar light irradiation. The optimized Pt-RGO-TiO₂ (1 wt % Pt and 10 wt % RGO) composite was found to show 14 fold increase in the photocatalytic hydrogen evolution efficiency under UV light irradiation and 20 fold increase under simulated solar light irradiation as compared to bare TiO₂ under UV light irradiation. The ternary photocatalyst showed very good recycle and reuse capability up to 4 cycles. The optimized Pt-RGO-TiO₂ was further tested for the enhanced photocatalytic degradation and mineralization of pharmaceutical pollutant namely β blocker Propranolol under UV as well as simulated solar light irradiation. The obtained results showed 79% and 94% reduction in COD of Propranolol under UV and simulated solar light irradiation respectively. The appreciable enhancement in the photocatalytic activity of the Pt decorated RGO-TiO₂ photocatalyst as compared to bare TiO₂ under UV and simulated solar light can be attributed to the use of maximum range of solar spectrum along with their excellent properties of charge separation by RGO and Pt.     

Synthesis of mesoporous g-C3N4/S-PAN π-conjugation heterojunction via sulfur-induced cyclization reaction for enhanced photocatalytic H2 production

Simultaneously extended π-conjugated system and provide abundant pore structure of semiconductor photocatalysts for hydrogen (H₂) production is highly desirable. Hence, a novel mesoporous sulfurized polyacrylonitrile modified g-C₃N₄ (g-C₃N₄/S-PAN) π-conjugation heterojunction is firstly fabricated by one-step strategy under the sulfur-induced cyclization reaction and pore-creating effect. Excitedly, the g-C₃N₄/S-PAN π-conjugation heterojunction extends the π-conjugated system in favor of speeding up the photogenerated electron transfer, which is due to strengthen the π-π interactions between the S-PAN and g-C₃N₄ and S-PAN is more apt to accept electrons. And the obtained g-C₃N₄/S-PAN π-conjugation heterojunction with mesoporous structure also provide abundant active sites for proton reduction. Accordingly, the g-C₃N₄/S-PAN-2 π-conjugation heterojunction shows the optimal photocatalytic H₂ evolution (PHE) activity (736.24 μmol h⁻¹g⁻¹), which is approximately 2.15 times higher than pristine g-C₃N₄. In addition, the relationships of the optical and photoelectrochemical properties with photocatalytic activity are revealed in depth based on the first-principles calculations of band structure and density of states (DOS). This work provides a new one-step strategy to obtain g-C₃N₄-based π-conjugation heterojunction with the unique microstructure for improving PHE activity.     

Amide–induced monodispersed Pt(100) nanoparticles loaded on graphene surface for enhanced photocatalytic hydrogen evolution

Using free and sustainable solar energy to produce hydrogen is the most promising strategy to resolve the environmental pollution and global energy crisis. The properties of sensitized matrix and co–catalyst, including the dispersibility, lattice structure and electrical performance, are usually two the decisive factors for photocatalytic hydrogen evolution. This paper reports a facile synthetic process of surface–clean monodisperse Pt(100) nanocubes supported on graphene surface using amide functional groups as induction sites. The prepared catalyst (AG/Pt(100)) not only incorporate plentiful amide functional groups that act as the dispersant and stabilizer into surface and edge of graphene, but also significantly dislodge the oxygen–containing functional groups, which hold strong promise for improving conductivity, carrier concentration and mobility of sensitized matrix. Simultaneously, the monodisperse Pt(100) nanocubes supported on graphene surface exposure more active sites. These results provide the necessary conditions for efficient catalysts. Without any pre–treatment, it exhibits high H₂ generation activity (553.7 μmol for 2 h) and apparent quantum efficiency (AQE) (33.9% at 430 nm) under visible light irradiation when Eosin Y is used as photosensitizer. These superior production H₂ activities can attribute to enhance the dispersion and conductivity of sensitized matrix, construct special geometry of Pt(100) nanocubes and prolong the lifetime of photogenerated electron.