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The presence of high nitrate (NO3−) concentration in natural water constitutes a serious issue to the environment and human health. Therefore, the development of low-cost, stable non-precious metal catalysts is imminent for efficient NO3- reduction. In this study, we prepared a Co3O4-TiO2/Ti cathode via combining sol-gel and calcination methods and evaluated its performance for electrocatalytic NO3- reduction. The dispersion of the Co3O4 catalyst particles was improved by the addition of PVP to the coating liquid. The presence of anatase could effectively stabilize Co3O4 and prevent the releasing of toxic Co ions into the solution. The Co3O4-TiO2/Ti cathode with the optimized performance for NO3- reduction could be prepared by four times coating at calcination temperature of 500 °C. The electrocatalytic reduction of NO3- was negligibly impacted by solution pH in the range of 3.0–9.0, while it could be facilitated by elevating the current density from 2.5 to 25 mA cm2. Ammonium ions were the main final NO3- reduction product, and the presence of Cl- was capable to oxidize ammonium ions to N2 due to the electrochemical production of reactive chlorine species. The electrochemical analyses, scavenging experiments and density functional theory calculations collectively confirm that NO3- reduction was mainly induced by the Co2+–Co3+–Co2+ redox process instead of being directly resulted from the electrons generated at the cathode. Unlike noble metal (e.g., Pd and Ag) based catalytic reaction systems, in the present Co3O4 mediated electrocatalytic reaction process, atomic H* would more favorably turn to H2 by Heyrovsky and Tafel routes and therefore contributed marginally to the NO3- reduction. Generally, this study provided a new paradigm for designing the stable and cost-effective cathode for NO3- reduction.

We aimed at producing a photocatalyst having UV–vis activity with residual energy storage ability in absence of irradiation. We synthesized a series of catalysts with Pt supported over mixed titanium-tungsten oxides (TiO2/WO3). The methods were spray dried assisted sol-gel and crash precipitation. TiO2 maintained its tetragonal anatase phase and WO3 its monoclinic structure. The hybrid samples (PtxTW, where x = 0–1.2 wt.%) have significantly higher BET surface area (204.0 - 283.0 m2/g) compared to control Pt0.8T (265.0 m2/g) and Pt0.8W (54.5 m2/g) samples. XPS analysis detected the presence of metallic platinum (Pt°), which actively takes part in the enhanced photons absorption of the photocatalyst, as depicted from UV–vis-DRS study. The Pt0.8TW- optimum Pt loading- is characterized by a visible absorption edge at 501.0 nm compared to the control Pt0.8T (444.0 nm) and Pt0.8W (540.5 nm). Microscopy images showed homogenous and uniform distribution of the oxides, and Pt particles and the FTIR analyses evidenced greater adsorption of OH− groups on the hybrid samples surface. In the activity tests, the Pt0.8TW outperforms the other samples in the aqueous degradation of the model pollutant methylene blue (MB) (78.0% and 56.0% in UV and visible light), with an additional hour of energy storage ability in absence of irradiation, then reaching a final degradation of 98.0% and 77.0% under UV and Visible light, respectively. In connection to the activity tests, scavenging experiments revealed that hydrogen peroxide (H2O2) and hydroxyl radicals (OH•) were the main species responsible for the pollutant degradation.

A novel hydrothermal route was developed to synthesize crystalline and hierarchically porous TiO2 at mild conditions under acidic/basic reaction environments. A good control over the key features of catalysts could be achieved by varying the pH of the starting solution (pH = 2–12) and type of acid during preparation. Crystalline, textural, and optical properties of photocatalysts were characterized in order to explore the connections between catalysts’ features and photoactivity. The activities of catalysts were evaluated for decomposition of methyl ethyl ketone (MEK) in a continuous flow photoreactor. To gain insight into the impact of main operating conditions on photocatalytic oxidation (PCO) processes, experiments were conducted at wide ranges of inlet concentration, relative humidity, and residence time. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed that yielded titania samples possess good crystallinity and mainly consist of anatase polymorph. Results of X-ray photoelectron spectroscopy (XPS) indicated that the population of hydroxyl groups on the surface of TiO2 declines as the acidity of hydrothermal solution increases. Hierarchical porous structure with ultra-long parallel macrochannels and large macropores (> 0.5 μm) could be directly observed in scanning electron microscopy (SEM). The multimodal porous structure offers higher light utilization, enhanced mass transport, and superior adsorption capacity for air pollutants. Photoluminescence spectroscopy revealed that the enhancement in crystallinity has an impact on the separation of photo-induced charge carriers. Moreover, a satisfactory linear correlation between the ability of photocatalysts to generate •OH and crystallinity could be found. Under the harshest operating condition (residence time = 0.012 s, relative humidity = 50%, concentration = 1000 ppb), the TiO2 synthesized in nitric acid (pH = 4) achieved the highest MEK removal efficiency, 36.9%, which substantially surpassed that of P25, 14.5%. Hierarchical porosity, optimum trade-off between surface area and crystallinity, existence of meso- and macropores, small crystal size, and high •OH generation ability could account for the superior performance. A tentative reaction pathway for MEK photodegradation and a health-risk index were put forward considering the by-products detected in the gas phase.

Mesoporous anatase crystal-silica nanocomposites with three-dimensional (3D) uniform and tunable intrawall mesopores connecting the mesochannels have been successfully prepared using the approach of first synthesizing titania-silica nanocomposites with ordered two-dimensional hexagonal mesochannels via “synchronous-assembly” of inorganic precursors with surfactant, then “extracting silica”. The uniform intrawall pores can be finely tuned in 3.6–5.6 nm by the strategy of adopting a large amount of silica in the walls, a very high crystallization temperature and mild silica extraction. The 3D interconnectivities of the mesochannels increase with extraction, but the mesostructures are retained intact. The average size of uniform anatase nanocrystals is 11.2 nm. This method is moderate, simple and facilely reproducible. The diffusion efficiencies of methylene blue (MB) in the mesostructures elevate with the intrawall mesopore size. The transient steady-state concentrations of •OH radicals rise fast with the intrawall pore size. The degradation rate of MB on the representative photocatalyst possessing large intrawall mesopores is extremely high (0.372 min−1), which is as high as 7.3 times that on the parent material, even up to 38.8 times that upon P25 photocatalyst. Our results clearly illustrate that the large intrawall mesopores play an overwhelming role in the increments of activities, while the matched adsorbability play an important synergetic role. Additionally, our photocatalysts are quite stable and reusable. Such results have not been seen in the literature till now. Furthermore, this approach is generally applicable to other metal-oxides-based materials, opening up a new avenue to rationally design and prepare mesostructures with 3D large intrawall mesopores, suitable adsorption and unexpected photocatalytic performances.

In this work we analyze two series of samples containing tungsten and titania as cations with a W/Ti atomic ratio from 0 to 0.5. The samples are prepared by a single-pot procedure, rendering in all cases high surface area powders having a dominant anatase crystalline phase. The materials were characterized by a combination of X-ray diffraction and photoelectron spectroscopies, UV–vis and Raman spectroscopies and morphological measurements. Particular effort was carried out in analyzing the way tungsten and titani-um interact in the materials through a microscopy analysis combining dark field Scanning transmission electron microscopy (HAADF-STEM) an X-ray energy dispersive spectrometry (XEDS). Overall the results are able to spot out the samples that show a truly doped character with tungsten exclusively located at (surface and bulk) lattice positions of the anatase structure, from composite catalysts where nanosized tungsten entities are supported over the dominant anatase phase. Activity of the materials in toluene and styrene photo-transformation reactions was measured through the reaction rate and the quantum efficiency observables. The study shows that quantitative comparison requires the stringent calculation of the quantum efficiency and that both the reaction rate and the apparent quantum efficiency can lead to misleading results in terms of the most active sample(s) as well as the (positive/negative) magnitude with respect to the bare titania reference. The quantum efficiency shows that doped samples can always improve titania reference sample(s) while this is not the case for composite samples.

It is highly desired to develop efficient visible-light-driven BiVO4-based nano-photocatalysts with recyclable feature by modulating photogenerated electrons and extending visible-light responses. Herein, a novel nanocomposite array has been successfully fabricated by uniformly decorating BiVO4 quantum dot (BiVO4-QD) with an average size of ∼5 nm onto rutile-TiO2 nanorod array (RTA) through the successive ionic layer adsorption and reaction processes, and exhibited high photocatalytic activity for converting CO2 to CO and CH4 under visible-light irradiation. The exceptional photoactivity is mainly attributed to the greatly-enhanced charge separation and prolonged charge lifetime by effectively transferring photogenerated electrons at the elevated conduction band bottom of BiVO4 to rutile-TiO2 nanorods as favorable electron acceptors and transport mediums by means of surface photovoltage technique, Mott-Schottky analyses and EIS measurements. Moreover, the photoactivity of optimized BiVO4-QD/RTA nanocomposite is further improved after loading SPR Au nanoparticles by promoting charge separation and extending visible-light responses, about 6.5-time higher than that of BiVO4-QD decorated anatase nanoparticle film. This work provides a feasible strategy to prepare easily reused and efficient BiVO4-based photocatalyst, which is also applicable to other semiconductors with low CB.

Hydrothermal technique was employed for the synthesis of N- and B-codoped TiO2 at different atomic percentages and calcination temperatures (350 and 400 °C). Borane tert-butylamine complex was used as a novel precursor for the dopant atoms. The photocatalytic activities of catalysts were evaluated for destruction of bisphenol A (BPA) spiked in clean water and in secondary treated wastewater influent (SWI) collected from the Groundwater Replenishment System GWRS (Orange County, CA, USA), the world's largest water purification system for indirect potable reuse. Results of X-ray photoelectron spectroscopy (XPS) revealed the incorporation of N and B atoms onto TiO2 lattice via substitution of O and/or Ti, and interstitial incorporation mechanisms. Carbon doping (graphite-like carbon; O-C = O) was also evidenced from XPS spectra. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) revealed pristine TiO2 and all doped TiO2 existed in anatase structure. The anatase phase of catalysts was further confirmed by simulation of selected area electron diffraction (SAED) of the catalysts and reported anatase TiO2 using the simulation software CrysTBox (v 1.10). Among all prepared catalysts, 2.0NBT-350 (N + B = 2.0%, calcination = 350 °C) possessed the smallest particle size (12.9 nm), largest BET surface area (108.5 m2/g) and highest visible-light absorption (i.e., λ > 400 nm). Simulated solar light/2.0NBT-350 system exhibited the maximum removal of BPA (0.1 μM) at the optimum catalyst dose of 0.8 g/L in clean water, over three consecutive degradation reuse cycles without any noticeable decrease in its photocatalytic activity. BPA was also successfully removed in SWI water, however with slower kinetics due to hydroxyl radical quenching effect of dissolved organic and inorganic species present in the SWI matrix. Degradation byproducts were identified by LC/Q-TOF-ESI-MS analysis. Six byproducts were found in the reaction mixture, with two compounds were newly identified in the current study. BPA oxidation routes comprised successive BPA hydroxylation, elimination of aromatic ring, ring opening, and cyclization of aliphatic compounds. This study is a promising demonstration for controlled design and synthesis of photocatalysts useful for environmental applications, especially for the treatment of BPA in wastewater effluents.

High-entropy oxides (HEOs), as a new family of materials with five or more principal cations, have shown promising properties for various applications. In this work and inspired by inherent defective and strained structure of HEOs, photocatalytic CO2 conversion is examined on a dual-phase TiZrNbHfTaO11 synthesized by a two-step high-pressure torsion mechanical alloying and high-temperature oxidation. The HEO, which had various structural defects, showed simultaneous photocatalytic activity for CO2 to CO and H2O to H2 conversion without the addition of a co-catalyst. The photocatalytic activity of this HEO for CO2 conversion was better than conventional photocatalysts such as anatase TiO2 and BiVO4 and similar to P25 TiO2. The high activity of HEO was discussed in terms of lattice defects, lattice strain, light absorbance, band structure, photocurrent generation and charge carrier mobility to activation centers. The current study confirms the high potential of HEOs as a new family of photocatalysts for CO2 conversion.

It is highly desired to develop an efficient g-C3N4-based photocatalyst for energy production under visible-light irradiation. Herein, it is shown that the optimized g-C3N4 nanosheet-based photocatalyst could exhibit exceptional photocatalytic activities for H2 evolution under visible-light irradiation, by ∼14-time improvement compared to that of bare g-C3N4 one. It is confirmed by the methods of transient-state surface photovoltage responses, transient-state PL spectra and electrochemical measurements that the exceptional photocatalytic activities are attributed to the unexpected synergistic effects of prolonging the charge lifetime and catalyzing H2 evolution by coupling nanocrystalline anatase TiO2 as a proper-energy platform to accept visible-light-excited electrons from g-C3N4 and by decorating a nano-sized noble metal as the co-catalyst respectively. Among three decorated noble metals (Ag, Au and Pt), to prolong the photogenerated charge lifetime is much meaningful for the used noble metal cocatalyst with weak catalytic function like Ag in H2 evolution. Using nanocrystalline SnO2 to replace TiO2 is also applicable for the synergistic effect. Moreover, it is clarified by the designed experiment on photocatalytic CO2 conversion to CD4 in the presence of methanol in D2O that the resource of evolved H2 is mainly from the adsorbed H2O other than the disassociated H+ from methanol.

In photoelectrochemical (PEC) water splitting systems, crucial obstacles limiting their performance are poor charge carrier dynamics and high recombination rate of photoexcited electron hole pairs. Here, we report that this issue can be alleviated by engineering a hybrid-junction that is composed of homo- and hetero- junctions. This strategy is performed by facile hand-spraying MoS2 over the surface of a anatase/rutile homo-junction TiO2 film on the Ti substrate to further form a hybrid-junction photocathode. By applying this photocathode into PEC reactor, enhanced catalytic activity is achieved under visible light (AM1.5 illumination of 300 W/m2) with hydrogen evolution reaction (HER) potential of −114 mV versus reversible hydrogen electrode (RHE) at 10 mA/cm2 and long-term stability of more than 10 times improvement comparing to ordinary electrode without the introduciton of hybrid-junction. The hybrid-junction that effectively regulates charge separation and transfer pathways is proven to be responsible for the enhanced activity. As an novel exploration, this hybrid-junction system comprising of low-cost, efficient charge separation and transfer, and visible light responsivity offers a new path for relative materials to boost their PEC performance.

The development of new technologies for carbon dioxide reduction, water splitting, and pollutant degradation has been a demanding challenge in the globe due to critical energy and environmental issues. Herein, we have successfully synthesized sulfur doped porous g-C3N4 (S-PCN) using ionic liquid, and then coupled nanocrystalline anatase TiO2 and Au-modified TiO2 to obtain nanocomposites. The amount-optimized 1 Au-6 T/6S-PCN nanocomposite exhibits exceptional visible-light activities for CO2 conversion to CH4, H2 evolution, and 2,4-dichlorophenol degradation, respectively by ∼32-time (365 μmol g−1h−1), ∼41-time (330 μmol g−1h−1) and ∼24-time (95% 10 mg h−1L−1) enhancement compared to the porous g-C3N4 (PCN). The calculated quantum efficiencies for CH4 production and H2 evolution are ∼4.67% and ∼3.34% at 420 nm wavelength. Based on these results, it is suggested that the exceptional photoactivities are attributed to the large surface area (100.5 m2g−1), extended visible-light response and enhanced charge separation via dopant induced surface-states and subsequently coupled Au-TiO2. Furthermore, the CO2 and H as active radicals would be dominant to respectively initiate CO2 and H2O reduction, and the produced OH plays a vital role in 2,4-dichlorophenol degradation. This work demonstrates that the designed PCN-based nanocomposites show promising applications in CO2 photo-reduction, water splitting, and pollutant degradation.

The photocatalytic reduction of CO2 with H2O to chemical energy-rich molecules (CH4 and CO) is significant to solve energy crisis. Herein, we have successfully fabricated the novel photocatalyst of bimetallic Pt-Ru alloy nanoparticles (NPs) selectively deposited on the {101} facet of TiO2 nanocrystal via the photon-assisted gas bubbling-membrane reduction (P-GBMR) method. The photogenerated electrons and holes are enriched on the coexposed {101}-39% and {001}-61% facets of anatase TiO2 nanocrystal, respectively. Noble metal (Pt, Ru and PtRu) NPs deposited on the TiO2-{101} facet can further improve the separation efficiency of photogenerated electron-hole pairs via the vectorial electron transfer of TiO2→PtRu. Pt/TiO2 catalytst with enriched surface photogenerated electrons shows the relative high formation rate of CH4 (22.9 μmol g−1 h−1) and H2 (52.8 μmol g−1 h−1), while Ru/TiO2 catalyst with strong adsorption/activation capability for CO2 prefers to improve the selectivity to CO product (65.1%). The possible mechanism for CO2 reduction is proposed and discussed: The formation of H-containing intermediate and the adsorption/activation property for CO2 are two important determining steps for improving photocatalytic CO2 reduction with H2O to CH4 product. PtRu/TiO2 catalyst with the synergic effect of Pt and Ru components exhibits the best catalytic performance for CO2 reduction with H2O to CH4 product under simulated solar irradiation, i.e., its formation rate of CH4 (38.7 μmol g−1 h−1) is about 29-fold of commercial P25, its selectivity to CH4 product is 93.7% and its apparent quantum efficiency for CO2 conversion is 0.98%. It expected to be a new heuristic on the development of high efficient photocatalysts for application to light-chemical energy conversion.

In this study, 0.1–4 wt.% Pd-loaded catalysts were synthesized via thermal decomposition of palladium (II) acetylacetonate (Pd(acac)2) at 210–310 °C or its photodecomposition under UV-LED irradiation using anatase TiO2 as a support. The catalysts were characterized by X-ray fluorescence, AAS, TEM, XPS, and CO chemisorption analyses and tested for CO oxidation at room temperature in a batch reactor both in the absence and presence of UV-LED irradiation. The effects of the Pd(acac)2 decomposition method and Pd content on the dark catalytic and photocatalytic activities were studied. Decomposition of Pd(acac)2 occurred with the formation of the metallic (Pd0) and oxidized (PdO) forms of palladium on the TiO2 surface for both employed methods. The photodecomposition resulted in an increased amount of metallic palladium. All of the synthesized Pd/TiO2 catalysts completely oxidized CO to CO2 at room temperature. UV-LED irradiation with a total irradiance of 10.4 mW/cm2 in the UVA region increased the rate of CO oxidation by up to 5 times compared to dark catalytic oxidation. Photodecomposition of Pd(acac)2 resulted in a higher activity of the Pd/TiO2 catalysts compared to the thermal decomposition method. The rate of CO oxidation under UV irradiation and under dark conditions monotonically increased as the Pd content increased due to the stability of high dispersion of Pd particles even with a high Pd content. The maximum value of the photonic efficiency was estimated to be 5.9%. CeO2, SiO2, and Al2O3 were also employed for the deposition of Pd to investigate the effect of a semiconducting support. For the CeO2-based catalyst, the activity under UV irradiation was higher than in the dark, but this effect was much lower compared to that of catalysts based on TiO2. By contrast, no substantial difference in the CO oxidation rate in the absence and presence of UV irradiation was observed for the non-semiconducting supports, SiO2 and Al2O3, confirming the photocatalytic oxidation of carbon monoxide for the TiO2- and CeO2-based catalysts.

A way to fulfill efficient exploitation of desired catalytic nature provided by V oxide is to modify its chemical structure through the incorporation of secondary transition metal species. This paper reports the use of Cu as a modifier of high-valent V oxide (V2O5) to produce a class of copper vanadates and their utilization as active sites for the selective catalytic reduction of NOX (X = 1 or 2) by NH3 (NH3-SCR). All catalysts contained ∼2 nm-sized copper vanadate particles highly dispersed on anatase with desired vanadate phases. The anatase-supported Cu5V2O10 provided a greater quantity of acid sites with improved redox character than Cu1V2O6, Cu2V2O7, and Cu3V2O8, thereby exhibiting the greatest NH3-SCR performance under ideal reaction conditions. Anatase-supported Cu3V2O8, however, was found to possess the most preferred surface properties among the catalysts post sulfation. This was evidenced by NH3-SCR runs of the catalysts under reaction conditions with H2O and SO2-including stream, where all catalysts were pre-sulfated by SO2 and O2 at elevated temperatures. The NH3-SCR performance of the optimum Cu3V2O8 on anatase was further promoted after sulfation of the catalyst with the optimum content of Sb promoter. The Sb promoter was verified to enhance the redox feature and minimize the interactions among catalyst surfaces and SO2/ammonium (bi)sulfates during the NH3-SCR, as evidenced by durability experiments. While showing N2 selectivities as ∼100% at ≤ 400 °C, the optimized Sb-promoted Cu3V2O8 on anatase showed high NOX conversions (≥ ∼85%) at ≥ 220 °C and outperformed the control vanadia-tungstate on anatase, which was used to simulate a commercial catalyst. This paper remarks the exploration of the variable structures of metal vanadates can be a good strategy to discover high-performance catalytic solids for the reduction of NOX species.

Semiconductor-based heterojunctions, widely applied in photocatalytic solar-to-chemical energy conversion, are advantageous for synergistically expediting photocatalytic reaction beyond individual the constituent components. Here we showed new quasi-core-shell In2S3/anatase TiO2@metallic Ti3C2Tx hybrids consisting of well-designed type-II heterojunction and non-noble metal-based Schottky junction with favorable charge transfer channels for efficient photocatalysis application. The mesoporous hybrids owned pleasurable visible-light absorption property and excellent capability in photogenerated exciton separation and carrier transport. Specifically, the hybridized photocatalyst with the additive Ti3C2Tx content of 16 mg (InTi-16) had excellent visible-light photocatalytic performance towards pollutant removal in water with a degradation rate of 0.04977 min−1, which was 3.2 and 6.2 folds higher than that of pure In2S3 and pure Ti3C2Tx, respectively. What's more, the photocatalytic degradation ability of InTi-16 had surpassed that of many other types of In2S3-based photocatalyst including In2S3/carbon nanotube (CNT), In2S3/reduced graphene oxide (rGO), In2S3/MoS2, and In2S3/TiO2 hybrids. The promising photocatalytic performance was strongly depended on the separation and diffusion of photogenerated exciton and carrier via a multitude of charge transfer channels due to the formation of double heterostructure (type-II heterojunction and Schottky junction). It had originated from the synergistic effects among the visible-light absorption of In2S3, the upward band bending of TiO2 and the favorable electrical conductivity of Ti3C2Tx. Prolonger electron lifetime favored for the generation of more strongly oxidizing radical (e.g. ·O2-) at the in-plane of Ti3C2Tx, and thus enhanced photocatalytic degradation ability. This work demonstrates that the TiO2/Ti3C2Tx can be a potentially novel platform for constructing efficient photocatalysts both for wide-ranging applications and unraveling the transfer behavior of photo-excited electrons based on charge transfer channels. MOE (Min. of Education, S’pore) EDB (Economic Devt. Board, S’pore)

A novel magnetic SO4/Fe-Al-TiO2 solid acid catalyst was synthesized for biodiesel production via the (trans)esterification of waste cooking oil (WCO). The nanocomposite catalyst was prepared by the sequential functionalisation of commercial rutile/anatase mixed phase TiO2 nanoparticles (NPs) with alumina as a buffer layer, and subsequently hematite to impart magnetic character, prior to sulfation with chlorosulfonic acid to introduce Bronsted acidity. XRD showed that the SO4/Fe-Al-TiO2 catalyst comprised titania (rutile and anatase phases), aluminium sulphate, and hematite nanoparticles, while electron microscopy revealed the layer-by-layer assembly of these components within the SO4/Fe-Al-TiO2 catalyst. FTIR confirmed the presence of surface sulphate groups SO42- and S2O72-/S3O102-, creating a predominantly Bronsted acid catalyst with high acid loading. The catalyst achieved 96 % fatty acid methyl ester (FAME) yield from WCO after 2.5 h of reaction at 90 °C, using 3 wt% of the magnetic catalyst, and a methanol:oil molar ratio of 10:1. SO4/Fe-Al-TiO2 was also effective for feedstocks containing up to 20 wt% of free fatty acid (FFA), and showed excellent stability for WCO (trans)esterification over 10 recycles.

One of the major set-backs in the selective CO methanation process, as the final clean-up step in removing residual CO from reformate gas feed, is the reverse water gas shift (RWGS) reaction. This reaction is an undesired reaction because, it runs parallel with the selective CO methanation reaction. This increases the CO outlet concentration. The catalytic performance of ruthenium supported on carbon nanotubes (CNTs), nitrogen doped carbon nanotubes (NCNTs), titania coated carbon nanotubes (NCNT-TiO2 and CNTs-TiO2) and TiO2 anatase (TiO2-A) for selective CO methanation was investigated. The feed composition relevant to reformate gas was used but in the absence of steam. The experiments were conducted within a temperature range of 100 °C and 360 °C. It was observed that carbon dioxide methanation was suppressed until CO methanation attained a maximum conversion for all the catalysts studied. The Ru/NCNT showed higher activity than Ru/CNT at all temperatures examined due to the nitrogen incorporation in the carbon domains. Both Ru/CNT and Ru/NCNT however promoted the RWGS reaction at temperatures above 250 °C. The Ru/CNT-TiO2 catalyst recorded the highest activity for both the CO and selective CO methanation followed by Ru/TiO2-A. The presence of titania on the carbon nanotubes significantly retarded the RWGS reaction from about −120% CO conversion to about 80% CO conversion, while selectivity towards methane increased in all catalysts with increasing temperature.

Visible light-induced selective oxidation of alcohols to aldehydes or ketones with atmosphere oxygen was triumphantly achieved devoid of any redox mediator. A paradigm of dye-sensitized TiO2 photocatalysis was capable of animating selective oxidation of a myriad of alcohols by 0.67 mol% of alizarin red S anchored onto TiO2 surface under the irradiation of green light-emitting diodes. In essence, both a robust dye like ARS and anatase TiO2 with a high specific surface area hold the key to unlock the high photocatalytic activity; and superoxide is pivotal in affording the selective oxidation product. This discovery could shed light on the design of visible light photocatalysis for selective organic transformations under ambient conditions by harvesting the cooperation between an organic dye and a metal oxide.

Imines are important intermediates for the synthesis of fine chemicals and pharmaceuticals. Design of a “green” oxidation catalyst to promote the direct oxidation of amines to imines by dioxygen have attracted great attention. Herein, we designed a catalyst of ordered mesoporous Au/M-TiO2 nanoparticles using a template-based approach. The as-prepared Au/M-TiO2 nanoarrays of anatase crystalline structure, with high specific surface area (222 m2/g), small pore size (∼2.1 nm) and ordered arrangements, gave dense array of ultrasmall pore-confined gold nanoparticles. The mesoporous Au/M-TiO2 exhibits particularly high visible light activity for photocatalytic selective aerobic oxidation of benzylamine to N-benzylidene benzylamine in a green approach by utilizing dioxygen as an oxidant in solvent-free conditions. The yield of N-benzylidene benzylamine can reach 1.73 mmol (TOF = 178.6 h−1, based on Au) in Au/M-TiO2 system, which is 1.5 and 1.6 times higher than that of the Au/P25 and Au/Acros anatase photocatalysts, respectively. Furthermore, we can also achieve high yield of N-benzylidene benzylamine (1.30 mmol, TOF = 134.2 h−1, based on Au) in air atmosphere. The confinement effect of the mesopores in Au/M-TiO2 facilitate the formation of O2− radicals and make the bi-molecular reaction highly preferred for promoting the high selectivity and conversion in plasmonic photocatalysis. Meanwhile, the Au/M-TiO2 with mesoporous structure can facilitate the efficient contact between the solvent and the nanomaterial, while possessing sufficient interfacial area for active oxidation reactions. This work paves a promising way to develop visible light-responsive TiO2-based photocatalysts with high specific surface area for highly efficient green oxidative organic synthesis.

A series of nitrogen-doped 2D-titanium dioxide nanosheets was synthesized via green and facile procedure from the lyophilized aqueous colloids of peroxo titanic acid by urea addition and annealing in the temperature range of 350–500 °C. Detailed structural characterization (SEM, TEM with EDX, XRD) of N-doped TiO2 confirmed their 2D-foil morphology composed of packed anatase nanocrystals. CHNS analysis showed that the total nitrogen content in the N-doped TiO2 nanosheets is comparable (0.3 wt. %), and as shown in the EPR measurements in solid state, the annealing temperature determines the character of the nitrogen species incorporated in the anatase lattice. Paramagnetic nitrogen bulk centers ( N b • ) dominate the X- and Q-band EPR spectra of the synthesized N-doped TiO2 annealed up to 400 °C, while NO species were detected in samples annealed at higher temperatures. The photoexcitation of the N-doped anatase nanosheets resulted in an intense increase of the N b • signal intensity, especially upon VIS-light exposure, reflecting the selective photoexcitation of the material via diamagnetic N b – centers. Nevertheless, the situation upon irradiation of dispersed systems is rather different and to link the information on the structure of the nanosheets with their photoinduced performance in suspensions, the indirect techniques of EPR spectroscopy were applied. Effective generation of paramagnetic reactive oxygen species (ROS) upon UV photoexcitation of the N-doped TiO2 nanopowders dispersed in water or dimethylsulfoxide was confirmed by EPR spin trapping technique. The VIS-light-induced ROS formation was significantly lower and correlates well with the results obtained by the photocatalytic decomposition of 4-chlorophenol upon VIS light. Even though the OH-induced capacity of N-doped TiO2 prevails upon UV exposure, the VIS irradiation evokes the formation of photoelectrons capable of the selective reduction processes as demonstrated by the one-electron reduction of 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) radical cation, where the form of nitrogen dopant (e. g. the presence of N b – / N b • ) in the anatase structure showed a clear effect on the reaction rate. The prepared visible-light active N-doped TiO2 nanosheets exhibiting also adequate UV photoactivity represent promising materials for further development of solar-light active photocatalysts.

Carbapenem-resistant Klebsiella pneumoniae (CP-Kp) is one of the most important opportunistic pathogens strongly associated with nosocomial infections. The capsule of CP-Kp not only contributes to its pathogenic potential but also ensures survival for bacteria in different environments and surfaces. Development of novel reactive nanomaterials can help to inhibit the survival of such microorganism and thereby their spreading in the hospital environment. In this work, the photocatalytic and antibacterial activities of PF-co-doped anatase TiO2 nanoparticles (NPs) were studied in details and related to the evolution of their structure and surface composition upon hydrothermal treatment at 250 °C for periods up to 12 h. Structural and morphological evolution were followed by X-ray diffraction, transmission electron microscopy while the surface composition was studied by X-ray photoelectron spectroscopy. Electron paramagnetic resonance measurements were carried out to reveal the formation of reactive oxygen species (ROS). Both OH and O2 − radicals as well as 1O2 were confirmed and quantitatively compared in different photoirradiated PF-TiO2 NPs dispersions. It was found that hydrothermal treatment increased the photocatalytic and antibacterial activity while PF-co-doping promoted the formation of OH radicals. By the application of PF-co-doping, the elevated level of OH led to rapid inactivation of CP-Kp.

Highly dispersed and thermally stable TiO2 quantum dots (TiO2-QDs) were achieved in the pore channels of SiO2 foams with large pore size (14–20 nm) via in-situ hydrolysis of Ti-alkoxide. Owing to the anchoring effect between TiO2-QDs and the pore-wall of SiO2 foam, both the TiO2 phase transformation from anatase to rutile and the aggregation of TiO2-QDs were effectively prohibited. The anatase TiO2-QDs anchored on the surface of silica foams could be well maintained with a ultrafine crystal size (

Highly-crystalline TiO2 nanoparticles coated on a suitable substrate make excellent photocatalysts for environmental applications. While electrophoretic deposition is frequently used to prepare such layers on a conductive support, this method often requires the presence of an additive to suppress nanoparticle agglomeration and increase particle surface charge. However, the presence of an additive can lead to contamination that negatively affects layer properties. To overcome this drawback, we developed an optimized electrophoretic method for the preparation of porous TiO2 layers, whose photocatalytic performance in the degradation of a toxic compound was analyzed. Our method enabled TiO2 layers (anatase, rutile and their mixture) to be quantitatively deposited on rigid substrates (stainless steel, FTO-glass and silicon wafers) without sintering and without the use of a dispersive additive. The photocatalytic performance of layers depended on the structural properties of titania particles, especially their allotropic form (anatase vs. rutile) and crystallinity, and on the presents of defects within the crystals. For well-developed crystals of anatase phase a high rate of the degradation of 4-chlorophenol and its almost complete mineralization were achieved. Owing to their excellent properties, especially stability and photocatalytic performance, the layers prepared by EPD are suitable for a broad range of environmental applications.

Progression in nano technology enormously influence on the synthesis of highly proficient photo materials and investigate their applications in diverse fields. A novel mesoporous heterostructure Ag-AgBr/HHST (hollow hierarchical silica-titania supported silver-silverbromide), synthesized by a facile one-pot micro emulsification method at controlled calcination temperature and investigated its photocatalytic performance for the degradation of methyl orange and aniline as ultra violet and visible light responsive material. Mesoporous Ag-AgBr/HHST was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV–vis. diffuse reflectance spectroscopy (UV–vis. DRS), Nitrogen adsorption-desorption analysis, photoelectron spectroscopic measurements (XPS) and photoluminescence spectral analysis (PL). The XRD, HRTEM and optical spectroscopic analysis justified the incredible effect of calcination temperature on the structure and morphology of nano composite. The results indicates, the photocatalyst synthesized at optimum calcinations temperature (550 °C) consist of small-hollow-spheres@big-hollow-spheres, leading the Ag and AgBr nano particles with an average particle size of 2–8 nm are homogeneously distributed on the surface of the hollow hierarchical silica-titania matrix, some particles are deeply embedded in HHST. Due to exceptional morphology, high surface area, small particles size and porous structure, the Ag-AgBr/HHST revealed elevated photocatalytic performance to degraded the 200 mL (200 ppm) of each methyl orange and aniline under simulated ultra violet as well as visible light irradiations in very short time intervals. Hollow hierarchical silica-titania offer high-quality conducting channel to pick up mass loading and enhance charge transfer. Whereas, strong connection of Ag and AgBr with silica-titania, feature highly active sites that causes synergetic effect capable for commendable photocatalytic performance compared with individual HHST, Ag-AgBr and (Degussa P25). While the photocatalyst obtained at 650 °C have some extant of phase conversion starting anatase to rutile phase of titania, and consist of big sized aggregated nano particles. The recycling runs experiments and reusability of the photocatalyst illustrate the venerable stability of the material that strengthens the synthesis of novel hollow hierarchical mesoporous compounds in this domains.

This paper introduces a droplet-based microfluidic approach, followed by several post-treatments, for the fabrication of TiO2 hollow shells with novel morphology and perfectly uniform size distribution, which were further decorated with platinum nanostructures to improve their photocatalytic activity and their ability to remove organic pollutants. In particular, a single-emulsion technique was used to emulsify an oil phase containing a titanium dioxide precursor, titanium n-butoxide (TBT), and a UV-curable polymer resin, trimethylolpropane triacrylate (ETPTA), into an aqueous phase. These emulsion droplets then readily underwent phase separation and sol-gel reaction at the emulsion interface, forming a TiO2 shell that would eventually rupture, release the ETPTA core, and form an anatase TiO2 hollow shell after UV, isopropanol, and thermal post-treatments. Compared with TiO2 hollow spheres reported in the literature, the TiO2 hollow shells produced here have a well-defined inner cavity that significantly improves their photocatalytic activity and allows for the selective introduction of advanced functions by the addition of metal co-catalysts like platinum. This new approach, by offering the ability to uniformly control the shape of the TiO2 photocatalyst and the ability to selectively introduce co-catalysts, offers an alternative platform for the design and fabrication of high-performance photocatalysts for efficient water purification.

Herein, we report a novel air-assisted carbon sphere combustion process to produce phase-tunable anatase-rutile (A/R) C/Pt-TiO2 photocatalysts for hydrogen generation and organic pollutant degradation under solar light irradiation. In the formed carbon/amorphous TiO2 core/shell structure, the carbon-core was acted as a fuel to prepare the mixed phase A/R TiO2 nanostructures. The A/R ratio of the TiO2 nanoparticles was tuned by varying the purged air flow during the combustion process. The obtained materials exhibited several unique properties not achievable using conventional methods, including anatase/rutile homojunction, co-existence of C and Pt/PtO and very high surface area, significantly improved charge separation and transfer characteristics towards excellent photocatalytic properties. Eventually, the photocatalytic activities of the obtained materials were found to be more than 23 and 17 folds higher than commercial TiO2-P25 for hydrogen generation and organic pollutant degradation, respectively.

Synthesizing titanium dioxide with energy storage ability represents a paradigm-shift for photocatalytic applications. We prepared titania tungstated photocatalysts (TiO2/WO3) by sol–gel and crash precipitation methods followed by spray drying to produce a micro-sized hybrid material. X-ray diffraction confirmed the tetrahedral and monoclinic crystalline structure of TiO2 and WO3 in the hybrid material calcined at 600 °C. Spray drying a suspension of titanium hydroxide alone creates spherical 20 μm TiO2 particles, whereas a suspension of ammonium paratungstate dissolved in hydrochloric acid produces 7 μm median size needle like WO3 particles. According to SEM-EDX images, spray drying both semiconductors together produces a homogeneously distributed mixture of the powders. The TW0.075 (titanium dioxide/tungsten oxide having 0.075 molar ratio of tungsten precursor) hybrid powder, with a surface area of 221 m2/g, 2.88 eV band gap energy, and 21.5% of anatase [001] facets (Raman analysis), decreased the electron-hole recombination with 1594 ns of carrier lifetime (PL-TRPL analysis). TW0.075 outperforms the rest of the samples in the UV degradation of the model pollutant methylene blue (MB), converting 90% MB in 100 min (30 min dark + 40 min light + 30 min dark), thus demonstrating energy storage ability in the absence of UV irradiation. Hydroxyl radicals (OH ) and superoxide anions (O2 −) are the species mainly involved in the pollutant degradation. We propose the transfer pathways mechanism of the photogenerated charge carriers in the hybrid samples.

Artificial photosynthesis efficiency for selective CO2 conversion to CH4 as chemical energy-rich molecule is dependent on the photogenerated charges separation and reactant adsorption property of photocatalyst. Here we report a novel fabrication of core-shell-structured photocatalysts of Pt/TiO2-nanocrystals wrapped by reduced graphene oxide (rGO) sheets ((Pt/TiO2)@rGO). The ultrafine anatase TiO2 nanocrystals with coexposed {001} and {101} facets acted as the fountain of the photogenerated charges primitively. Pt nanoparticles (NPs) deposited on the TiO2 nanocrystals can gather and transfer the stimulated electrons originated from anatase TiO2 nanocrystals. The all-solid-state electron multiple transmission (EMT) system with TiO2-nanocrystal(core)-Pt(mediator)-rGO(shell) nanojunction is not only favorable to the vectorial electron transfer of TiO2 → Pt → rGO and enhance the separation efficiency of photogenerated electrons and holes, but also the surface residual hydroxyl and extended π bond of wrapping rGO sheets can improve the adsorption and activation capabilities for CO2 reactant. (Pt/TiO2)@rGO ternary photocatalysts exhibit excellent performance for the multi-electron process of selective photocatalytic CO2 conversion to CH4. Among the prepared catalysts, (Pt/TiO2)@rGO-2 catalyst shows the highest photocatalytic activity and selectivity for CO2 conversion, i.e., the formation rate of CH4 is 41.3 μmol g−1 h−1 and the selectivity of CO2 conversion to CH4 product is 99.1%, and its apparent quantum efficiency for CH4 product is 1.93%. As a heuristic the fabrication of core-shell structured (Pt/TiO2)@rGO photocatalysts will stimulate more novel ideas for application to light-chemical energy conversion.

In this research, two interesting phenomena were reported and analyzed: First, two-dimensional tiny titania nanoplates (4–5 nm lateral size, 0.4–0.5 nm thickness) with rich edge-defects were found to self-assemble into free-standing thin sheets with large lateral size in a freeze-drying process with the aid of linker; Second, when subjected to a moderate hydrogenation treatment, these self-assembled sheets could be crystallized into integral anatase sheets while the edge-defects of the building blocks were maintained on the surface or inside the body of the crystal and the flexible sheet-like shape were also maintained. Based on these observations, a method for scalable preparing free-standing defect-rich TiO 2 with a two-dimensional sheet-like morphology was proposed. The defects (oxygen vacancies) endowed the TiO 2 a grayish-black color and visible-light responsibility. By using the dispersion of these defect-rich anatase sheets, a film could be densely deposited on flexible substrates in a layered structure and showed an efficient performance in acetaldehyde decomposition under the irradiation of visible light. Since it has always been a technical challenge to prepare crystallized visible-light-driven TiO 2 films on plastic substrates with a low heat tolerance, this work may also provide a new approach to this problem.

In this article, thin solid films are processed via pulsed-pressure metal organic chemical vapour deposition (PP-MOCVD) on FTO substrates over a range of processing times to produce a range of thicknesses and microstructures. The films are highly nanostructured anatase-rutile TiO2 composite films with unique single crystal dendrites. After annealing, carbon was removed, and materials showed improved water splitting activity; with IPCEs above 80% in the UV, photocurrents of ∼1.2 mA cm−2 at 1.23 VRHE at 1 sun irradiance and an extension of photoactivity into the visible range. The annealed material exhibits minimal recombination losses and IPCEs amongst the highest reported in the literature; attributed to the formation of a high surface area nanostructured material and synergetic interactions between the anatase and rutile phases.

In this study, rhodium and antimony doped nanorod (RS-TONR) was prepared by a molten salt solid state chemical reaction, and TiO2 nanorod and titanate nanotube (RS-TONR/TiNT) composite photocatalyst was synthesized by a hydrothermal method for different reaction times. The structural and chemical analyses of nanomaterials were performed by FE-SEM, XRD, UV-DRS and surface BET characterizations. The XRD and HR-TEM data confirmed that the as-synthesized material had mixed phase of TiO2 nanorod and Titanate nanotube (RS-TONR/TiNT). The photocatalytic activity of the composite photocatalyst was observed over the degradation of Orange (II) dye under visible light irradiation. Acid treatment and copper loading was conducted to enhance the surface property of RS-TONR/TiNT sample. The formation of TiO2 nanoparticle with anatase phase was observed by TEM and XRD analysis. The TEM mapping data also confirmed that copper oxide nanoparticles were well dispersed on the surface of titanate nanotubes. These dispersed nanoparticles were observed by XPS and STEM characterizations. The higher removal efficiency of Cd2+ ions was observed over the acid treated and untreated Cu3-TNP/TiNT/RS-TONR in the presence of Orange (II) dye. A higher photocatalytic activity of acid treated and Cu3-TNP/TiNT/RS-TONR was simultaneously obtained in the presence of cadmium ions during the degradation of Orange (II) dye.

Photocatalytic oxidation of gaseous ammonia (NH3) at room temperature is an efficient method for the elimination of NH3 emitted from indoor and outdoor sources, such as decorative materials, intensive livestock farming, chemical processes, etc. Herein, we prepared the anatase TiO2 with clean dominant {001}, {101} and {010} facets, and tested their photocatalytic activity for NH3 oxidation. The test results show that the photocatalytic activity order for NH3 oxidation is revealed as {001} > {101} > {010}. The catalysts were characterized by XRD, FE-SEM, XPS, UV–vis, in situ DRIFTS and TPD methods. It is indicated that TiO2 with dominant {001} facets has the highest separation efficiency of the photogenerated charges among three catalysts. Since the photogenerated holes is responsible for initiating the first step of NH3 oxidation, the TiO2 with dominant {001} facets demonstrated the exceptional activity. In addition, the photocatalytic oxidation of NH3 possibly follow the photo-iSCR mechanism. The photogenerated electrons activate O2 and then participate in the formation of reactive intermediate NOx followed by the photo-NH3-iSCR to final products. The present study will improve our understanding about the performance of anatase TiO2 for photocatalytic oxidation of NH3.

Nanostructured TiO2 hollow spheres (THS) were prepared via a simple hydrothermal method with titanium butoxide, ethanol, urea, and ammonium sulphate. The effects of Ti/ethanol, and reflux temperature on the morphological properties of the nanostructured THS were investigated. An impregnation method was subsequently employed to load metals such as Cu, Co, Cr, Ag, and Ni on the optimized THS, followed by calcination in H2/N2 at 450 °C for 4 h. The morphological properties of the prepared samples were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy (UV/vis). The SEM and TEM pictures showed that the Ti/ethanol ratio of 1:10 resulted in the formation of uniform hollow spheres. The XRD spectre revealed that phase transformation took place as the reflux temperature was increased, with pure anatase TiO2 hollow spheres being formed at 200 °C. The BET surface areas of the calcined photocatalysts were in the range of 80.6–116 m2/g−1. The UV/vis spectra of the photocatalysts showed that loading of transition metals reduced the band gap of the THS. The activities of the prepared catalysts were tested for hydrogen production via photocatalytic reforming of glycerol under solar irradiation. The improved hydrogen evolution from photocatalytic reforming of glycerol was attributed to: the high surface area which enhanced the adsorption of glycerol onto the surface of photocatalysts; high crystallinity and the reduced band gap which improved the solar light harvesting; the hollow chamber within the TiO2 spheres which produced multiple reflection of the light harvested, thus producing efficient electron/hole pair formation; and the detailed composition of the solids retarded the electron/hole recombination by trapping the electrons generated during the photo excitation of the photocatalysts, and thereby promoted their activity.

Modification of TiO2 with copper oxides clusters (CuOx-TiO2) induces visible-light absorption and enhances its activity. In this work, we investigated the CuOx-anatase and CuOx-rutile for the photocatalytic oxidation of gaseous NH3 under visible light. In contrast with the widely reported results that CuOx-anatase displays higher performance than CuOx-rutile in photocatalytic oxidation or reduction, we surprisingly observed that CuOx-rutile is able to oxidize NH3 efficiently under visible light irradiation, while CuOx-anatase shows no activity. Further characterizations showed that visible-light inclines to drive the VB electrons of rutile TiO2 to CuOx at the interface between rutile TiO2 and CuOx, while it drives the electrons of CuOx to anatase TiO2 at interface between anatase TiO2 and CuOx. DFT calculations revealed that the interaction between CuOx and TiO2 is markedly different in CuOx-anatase and CuOx-rutile, which induces the differences in the electronic distribution of interfacial Cu, O and Ti atoms, resulting in the distinct direction of charge transfer.

Strong metal-support interaction (SMSI) is regarded as one of the most important concepts in heterogeneous catalysis; however, few researches are focused on SMSI regulating the support structure, properties and their roles on the catalytic performance. Herein, anatase TiO2{001} nanosheets pretreated in different atmosphere were used to load Pt for reverse water gas shift reaction. The Pt/N-doped TiO2 catalysts exhibited significantly superior catalytic performance. The investigation demonstrated that defects and doped-N enhance the Pt dispersion while Pt and SMSI in turn promote defects regeneration during activation in H2. During reaction, surface defects enable CO2 activation to generate active intermediates which easily decompose into CO. Furthermore, the small Pt particles and SMSI facilitate H2 dissociative adsorption and spillover to replenish both surface defects and bulk Ti3+. Besides, a novel reaction route has been observed that the stable bulk Ti3+ in N-doped TiO2 migrate and transform to surface defects, enhancing catalytic performance.

Visible light photocatalysis could offer an eco-friendly alternative for selective transformation of organic molecules. Herein, a cooperative system is created with alizarin red S (ARS), TiO2 nanotubes (TNTs), and an extra redox mediator. The electron transfer between oxidatively quenched ARS-TNTs and the redox mediator is the key to secure cooperative photocatalysis. The selective aerobic oxidation of primary and secondary amines was constructed by cooperative photocatalysis of ARS-TNTs with 2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (TEMPO+BF4−) driven by green light. Specifically, the activity of anatase TNTs could reach about 2.2 times that of the P25 (Aeroxide P25) TiO2 precursor. Due to increased polarity, TEMPO+BF4− serves more efficiently for electron transfer than (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO), conferring above 1.5 times of activity that of TEMPO for the selective aerobic conversion of amines. This work features the potential of designing redox mediators in amplifying cooperative photocatalysis driven by visible light.

Quantitative assessments of electron and hole transfer dynamics with water on anatase nanocrystalline TiO2 films were conducted by employing a series of transient absorption spectrometers. For water reduction reactions, both conduction band and trapped electrons decay with two different single exponential components with the difference in time scale of 6∼7 orders of magnitudes. The faster reaction occurs in 8–16 ns, while the slower component shows a lifetime of 0.1∼1.4 s. Pt nanoparticle deposition on the TiO2 surface switches the slower single exponential reaction to a stretched exponential with an accelerated half lifetime of 2–7 ms, indicating that this slower reaction is limited by the electron trapping-detrapping movements inside the TiO2. Water oxidation reactions occur multi-exponentially from 100 ns to 200 ms with a half lifetime of 10 μs. Pt on the TiO2 surface catalyses water oxidation, occurring from 25 ns with a half lifetime of 8 μs.

In this work, we constructed a red phosphorus (RP)/TiO2 composite system via a chemical vapor deposition strategy. The evolution of the fibrous phased RP nanorods on the surface of anatase TiO2 spheres was rationally adjusted by controlling the composition of precursors. The optimal RP/TiO2 composite exhibited a significantly enhanced visible-light-driven photocatalytic H2 generation rate of 681 μmol h−1 g−1. The tightly interior surface bonding between RP and TiO2 greatly promoted the efficient charge transfer and redistribution by suppressing the charge recombination and self-trapping processes within TiO2, resulting in prolonged lifetimes of the active charges during the photocatalytic process as investigated in detailed using femtosecond time-resolved transient absorption (fs-TA) spectroscopy.