Highly stabilized Ag2O-loaded nano TiO2 for hydrogen production from glycerol: Water mixtures under solar light irradiation

Nano TiO₂ prepared by a hydrothermal method and silver-loaded nano TiO₂ prepared by impregnation were studied for the photocatalytic production of hydrogen from glycerol:water mixtures. The structural characteristics were revealed using XRD, EDAX, DRS, TEM, XPS, BET surface area and Raman techniques. The photocatalytic hydrogen production has been investigated under solar light irradiation. Effects of nano TiO₂ calcination temperature, silver loading, photocatalyst content, light source and Ag oxidation state on hydrogen production have been systematically studied. Maximum hydrogen production of 200 μmol h^?1 g^?1 is observed on 4wt% silver-loaded nano TiO₂ catalyst in pure water and the maximum hydrogen production of 7030 μmol h^?1 g^?1 is observed on 3wt% silver-loaded nano TiO₂ catalyst in glycerol: water mixtures. Silver-loaded nano TiO₂ reduced and photodeposited catalysts show similar hydrogen production activities in glycerol: water mixtures under solar irradiation. The optimum catalyst modified with conducting carbon materials (graphene oxide, graphene, carbon nanotubes) by a solid-state dispersion method were also studied for hydrogen production under solar light irradiation. Compared with pure nano TiO₂, a 3wt% silver-loaded nano TiO₂/graphene composite exhibited an approximately 17-fold enhancement of hydrogen production leading to hydrogen production rates of 12,100 μmol h^?1 g^?1. Based on the characterization results and hydrogen production activity on these catalysts, a structure–activity correlation has been proposed wherein the interacting Ag₂OAg phases on the surface of nano TiO₂ play an important role in maintaining a high hydrogen production activity under solar irradiation.     

Enhanced photocatalytic hydrogen production activity of noble metal free MWCNT-TiO2 nanocomposites

Nanocomposite photocatalysts, MWCNT-TiO₂ were prepared by hydrothermal method. The photocatalysts were characterized by X-ray diffraction, Transmission electron microscopy (TEM), Raman spectroscopy, UV-Visible diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy to understand the crystal structure, morphology, and optical properties. The catalyst synthesis parameters such as calcination temperature and loading of MWCNTs were optimized for better hydrogen (H₂) production in 5 vol% glycerol aqueous solution under UV-visible light irradiation. Among the prepared nanocomposites, 0.1 wt% CNT loaded TiO₂ calcined at 450 °C for 2 h showed the highest H₂ production rate of 8.8 mmol g^?1 h^?1. This higher H₂ production rate obtained can be ascribed to effective utilization of the photo generated electrons and holes for redox reactions.     

A sea cucumber-like nanoporous TiO2 modified by bimetal PtAu through the dealloying for water splitting

Bimetal PtAu modifying nanoporous TiO₂ composites are prepared by dealloying. X-ray diffraction is used to determine the phase constitution. The specific surface area and mesoporous pores are measured by Brunauer-Emmett-Teller. X-ray photoelectron spectroscopy, photoluminescence spectroscopy, UV–Vis diffuse reflectance spectroscopy and Raman spectroscopy are employed to analyse the mutual synergy between Pt and Au. The hydrogen generation rate is measured to determine the photocatalytic performance. The results reveal that TiO₂ is the anatase structure and possess a sea cucumber-like morphology with a large specific surface area. The hydrogen generation rate is 1.745 mmol h^?1 g^?1 for the dealloyed Al₉₂Ti_7.86Pt_0.04Au_0.1 ribbons under the full spectrum irradiation. This value is 29.6 times, 4.4 times and 1.8 times those of the dealloyed Al₉₂Ti₈, Al₉₂Ti_7.9Au_0.1, and Al₉₂Ti_7.96Pt_0.04 ribbons, respectively. The above results indicate that the addition of a small amount of Au and Pt significantly enhances the photocatalytic activity for H₂ production. The Au promotes the absorption of visible light, and Pt serve as an electron sink for effective electron-hole pairs separation during the photocatalytic process. It is a feasible and an effective strategy to take full advantages of respective virtues of noble metals and their strong interactions to enhance photocatalytic activity.     

Preparation of direct Z-scheme Bi2WO6/TiO2 heterojunction by one-step solvothermal method and enhancement mechanism of photocatalytic H2 production

Direct Z-scheme Bi₂WO₆/TiO₂ heterojunction photocatalyst was prepared by one-step solvothermal method. The catalyst was characterized by XRD, TEM, XPS, UV–Vis DRS, photoluminescence spectroscopy and photoelectrochemical studies. The photocatalytic hydrogen production experiments show that Bi₂WO₆ did not generate H₂ and the H₂-production rate of TiO₂ is only 0.1 mmol⋅g⁻¹h⁻¹. The hydrogen production rate of the Bi₂WO₆/TiO₂ heterojunction photocatalyst reaches 12.9 mmol⋅g⁻¹h⁻¹, which is 129 times that of TiO₂. Compared with TiO₂, the enhanced H₂-production activity of the heterojunction catalyst can be attributed to the wider light absorption range and the efficient separation and migration of carriers at the close contact interface between Bi₂WO₆ and TiO₂. Based on the work functions of Bi₂WO₆, TiO₂ and their heterojunctions, combined with the results of electron paramagnetic resonance spectroscopy and Mott-Schottky measurements, the photocatalytic H₂ production mechanism of Z-scheme heterojunction Bi₂WO₆/TiO₂ was proposed. This work provides an easy and simple way to design a binary Z-scheme photocatalyst with efficient catalytic H₂-production activity without electron mediators.     

LED light-induced enhanced photocatalytic hydrogen evolution on Au@TiO2 core–shell modified by nitrogen doping and reduced graphene oxide

This study focused on the large band gap of TiO₂ for its use as a photocatalyst under light emitting diode (LED) light irradiation. The photocatalytic activities of core–shell structured Au@TiO₂ nanoparticles (NPs), nitrogen doped Au@TiO₂ NPs, and Au@TiO₂/rGO nanocomposites (NCs) were investigated under various light intensities and sacrificial reagents. All the materials showed better photocatalytic activity under white LED light irradiation than under blue LED light. The N-doped core–shell structured Au@TiO₂ NPs (Au@N–TiO₂) and Au@TiO₂/rGO NCs showed enhanced photocatalytic activity with an average H₂ evolution rate of 9205 μmol h^?1g^?1 and 9815 μmol h^?1g^?1, respectively. All these materials showed an increasing rate of hydrogen evolution with increasing light intensity and catalyst loading. In addition, methanol was more suitable as a sacrificial reagent than lactic acid. The rate of hydrogen evolution increased with increasing methanol concentration up to 25% in DI water and decreased at higher concentrations. Overall, Au@TiO₂ core–shell-based nanocomposites can be used as an improved photocatalyst in photocatalytic hydrogen production.     

CuOCr2O3 core-shell structured co-catalysts on TiO2 for efficient photocatalytic water splitting using direct solar light

Synthesis of core-shell structured CuOCr₂O₃ nanoparticles as co-catalyst to improve the photocatalytic hydrogen evolution performance of TiO₂ was demonstrated. The effect of co-catalyst loading on TiO₂ and the nature of the reactor was found to be more significant for H₂ production under direct solar light. The formation of 9.3 nm Cr₂O₃ shell over CuO core in the CuOCr₂O₃ nanostructured co-catalyst was confirmed using transmission electron microscopy. A very high H₂ production rate of 82.39 and 70.4 mmol h^?1 g^?1_cat was observed with quartz and pyrex reactors under direct solar light of irradiation 96–100 mW/cm², respectively. This is almost three times higher than that of bare TiO₂ under similar experimental conditions. The core-shell co-catalyst loaded on TiO₂ by simple mechanical mixing method which is useful for bulk scale synthesis in practical applications. The observed high H₂ production was explained with plausible mechanism where the synergic effect of CuOCr₂O₃ co-catalyst loaded TiO₂ surface that reduces the effective charge carriers recombination and impeded backward reaction by the Cr₂O₃ thin layer. The presence of Cu²⁺ and absence of Cu⁺ and metallic Cu was confirmed using XPS analysis. The effect of co-catalyst loading and sacrificial agent concentration on the photocatalytic hydrogen production was also reported. The stability of the CuOCr₂O₃ core-shell NPs loaded TiO₂ photocatalyst under the direct solar light was examined by continuous cycling for three days and it was found to be 81 and 70% of photocatalyst activity is retained after 3 days in the quartz and pyrex reactor systems, respectively.     

Remarkable charge separation and photocatalytic efficiency enhancement through TiO2(B)/anatase hetrophase junctions of TiO2 nanobelts

Light harvesting and charge separation are both significant to the photocatalysis, but it is challenging to synchronously realize both in a single-component material. The surface coarsened TiO₂ nanobelts with TiO₂(B)/anatase hetrophase junctions and large BET surface area are prepared via a hydrothermal/annealing method. The presence of surface coarsened nanobelt structure enhances the light absorption through reflection/refraction of light. The TiO₂(B)/anatase hetrophase junctions can efficiently promote the separation of photoinduced electrons and holes pairs and therefore decrease the charge recombination. The large BET surface area provides abundant active sites for the absorption and diffusion of reactants. As a consequence, the obtained TiO₂ nanobelts exhibit an enhanced photocatalytic H₂ evolution activity at the optimal annealing temperature (450 °C) with Pt as co-catalysts (0.786 mmol h⁻¹g⁻¹), exceeding that of pure anatase TiO₂ nanobelts (TiO₂ nanobelts-600 °C, 0.265 mmol h⁻¹g⁻¹). Interestingly, TiO₂ nanobelts-450 °C still show a high hydrogen evolution rate of 0.601 mmol h⁻¹g⁻¹ in the absence of co-catalysts.     

Hierarchical spheres assembled from large ultrathin anatase TiO2 nanosheets for photocatalytic hydrogen evolution from water splitting

We report the synthesis of TiO₂ hierarchical spheres (THS) with large specific surface area via a facile one-pot solvothermal method. The as-prepared THS are self-assembled by ultrathin TiO₂ nanosheets with thickness of several nanometers and they show a uniform spherical morphology with an average size of 500–700 nm. However, the as-prepared light yellow THS exhibit inferior photocatalytic activity for hydrogen evolution from water splitting due to the poor crystallization of TiO₂ and the existence of oxygen vacancies. Significantly, a subsequent thermal treatment improves the crystallinity of THS, reduces the oxygen vacancies, and thereby enhances the photocatalytic performance. It demonstrates that the sample annealed at 550 °C (THS550) exhibits the highest photocatalytic activity, about 5 times higher than that of commercial TiO₂ nanoparticles (CTiO₂). Moreover, the THS550 sample loaded with 1 wt% Pt exhibits an hydrogen evolution rate as high as 17.9 mmol h^?1g^?1, and the corresponding apparent quantum efficiency has been determined to be 28.46% under 350 nm light irradiation.     

Fabrication of TiO2 nanoflowers with bronze (TiO2(B))/anatase heterophase junctions for efficient photocatalytic hydrogen production

Light harvesting and charge separation are both significant in the photocatalysis, but it is challenging to synchronously realize both in a single-component material. The novel porous TiO₂ nanoflowers (NFs) photocatalysts with stable bronze (TiO₂(B))/anatase heterophase junctions and large pore sizes are prepared via a hydrothermal/annealing method. The presence of porous nanoflower structure enhances the light absorption through reflection/refraction of light. The stable TiO₂(B)/anatase heterophase junctions can efficiently promote the separation of photoinduced electrons and holes pairs and therefore suppress the charge recombination. The large pore sizes provide multi-level channels for the absorption and diffusion of reactants. With the increase of annealing temperatures from 350 to 550 °C, the H₂ evolution activity is promoted. However, overhigh annealing temperature (650 °C) cause the broken of nanoflower structure and TiO₂(B)/anatase heterophase junctions, thus inducing even decrease of H₂ evolution activity. As a consequence, the obtained TiO₂ NFs exhibit an enhanced photocatalytic H₂ evolution activity at the optimal annealing temperature (550 °C) with Pt as co-catalysts (5.013 mmol h⁻¹g⁻¹), exceeding that of TiO₂ NFs without annealing (0 mmol h⁻¹g⁻¹) and pure anatase TiO₂ NFs (TiO₂ NFs-650 °C, 4.722 mmol h⁻¹g⁻¹), respectively. Interestingly, TiO₂ NFs-550 °C still show a high hydrogen evolution rate of 4.317 mmol h⁻¹g⁻¹ in the absence of co-catalysts.     

Evaluation of in-situ formed La2O3–TiO2–La2O2CO3 nanocomposite photocatalyst for H2 production

The photocatalytic evolution of H₂ over La₂O₃ decorated TiO₂ catalyst was examined under solar light. It was observed that during the course of the reaction, the transformation of La₂O₃/TiO₂ into La₂O₃–TiO₂–La₂O₂CO₃ occurred and these species effectively suppressed electron-hole pair recombination by forming electron trapping centres on the surface, resulting in an increased visible light absorption and improved H₂ yield. The 2 wt%La₂O₃/TiO₂ nanocomposite demonstrated better H₂ yield (～8.76 mmol (g_cat)^?1) than the bare TiO₂ (～1.1 mmol (g_cat)^?1). The catalyst was stable even after several consecutive recycles with no substantial loss of hydrogen production rate. The H₂ rates were correlated with the physicochemical characteristics of the catalysts examined by BET–SA, H₂-TPR, XRD, UV-DRS, Raman spectroscopy, FTIR, HRTEM, EPR and PL spectroscopy.     

Crystalline-to-amorphous transformation of tantalum-containing oxides for a superior performance in unassisted photocatalytic water splitting

Crystalline tantalum-containing oxides are usually taken as the advanced photocatalysts for water splitting. How about the amorphous counterparts? In this work, a transformation of crystalline Na₂Ta₂O₆ (CNa₂Ta₂O₆) to amorphous TaO_x (Am-TaO_x) was achieved by a facial hydrothermal method. We proposed a transformation mechanism based on nucleation-dissolution -recrystallization and further intensified the influence of base concentration on the composition, crystallinity, and morphology (CCM) as confirmed by XRD, TEM, EDS. N₂-physisorption, Raman, IR, and XPS analysis. It is found that when comparing to the crystalline counterparts, amorphous samples possessed higher surface area, abundant surface hydration layers and H⁺ adsorption, showing an unassisted photocatalytic water splitting with a rate of 70 ± 7 μmol g^?1 h^?1, much larger than that of 15 ± 1 μmol g^?1h^?1 of CNa₂Ta₂O₆, 11 ± 1 μmol g^?1h^?1 of crystalline Ta₂O₅ (CTa₂O₅), 30±2 μmol g^?1h^?1 of mixture with crystalline Ta₂O₅ and amorphous Na_xTa_yO_z (CTa₂O₅/Am-Na_xTa_yO_z), and even 4.6 × 10^?4 μmol g^?1h^?1 for commercial TiO₂. This observation is beneficial from the short diffusion paths of amorphous state for charge carriers, amount of catalytic sites, and stronger reducing ability. These findings develop a novel and efficient pathway towards synthesizing the different CCM of tantalum-containing compounds under hydrothermal conditions and could open opportunities for further investigating the photocatalytic property of tantalum-containing materials.     

Improved photocatalytic H2 production assisted by aqueous glucose biomass by oxidized g-C3N4

Chemically modified g-C₃N₄ for the photocatalytic H₂ evolution from water was explored. Bulk g-C₃N₄ was treated in hot HNO₃ aqueous solution to obtain the oxidized material (o-g-C₃N₄), tested in water containing glucose as model water-soluble sacrificial biomass, using Pt as co-catalyst, under simulated solar light. The behaviour of o-g-C₃N₄ was studied in relation with catalyst amount, Pt loading, glucose concentration. Results showed that H₂ production is favoured by increasing glucose concentration up to 0.1 M and Pt loading up to 3 wt%, and it resulted strongly enhanced using small amount of o-g-C₃N₄ (0.25 g L^?1). o-g-C₃N₄ possesses superior photocatalytic activity (～26-fold higher) compared to pristine g-C₃N₄, with H₂ evolution further improved by ultrasound-assisted exfoliation and evolution rates up to ca. 1370 μmol h^?1 per gram of catalyst, with excellent reproducibility (RSD < 6%, n = 3). Significant production was observed also in river water and seawater, with results far better (up to ca. 2500 μmol g^?1 h^?1) compared to commercial AEROXIDE^® P25 TiO₂ under natural solar light.     

In-situ photo-deposition CuO1−x cluster on TiO2 for enhanced photocatalytic H2-production activity

CuO_1?x cluster-modified TiO₂ (CuO_1?x/TiO₂) photocatalysts were prepared by an in-situ photoreduction deposition of Cu on TiO₂ powder support using copper acetate as a Cu source. The prepared samples without any Pt co-catalyst present an especially high photocatalytic H₂-evolution activity under solar light irradiation with 5% glycerol as sacrificial agent. The optimal CuO_1?x/TiO₂ catalyst with only 1 wt% CuO_1?x exhibits a high activity of 1725 μmol h^?1 g^?1 for H₂ evolution, which reaches 120 times that of TiO₂. The high photocatalytic activity of H₂ production is attributed to the highly dispersed CuO_1?x nano clusters on the surface of the TiO₂. In addition, Pt/CuO_1?x/TiO₂ was also prepared by loading Pt on CuO_1?x/TiO₂ sample, and its photocatalytic hydrogen evolution activity is enhanced 1.8 times compared with that of Pt/TiO₂ for overall water splitting reaction under solar light, demonstrating that a small amount CuO_1?x wondrously improves the photocatalytic activity of Pt/TiO₂ for overall water splitting reaction. This paper reports an economic and simple approach to prepare a photocatalyst with high hydrogen-production activity.     

Enhanced photocatalytic hydrogen evolution from reduced graphene oxide-defect rich TiO2-x nanocomposites

Solar-driven photocatalytic hydrogen generation by splitting water molecules requires an efficient visible light active photocatalyst. This work reports an improved hydrogen evolution activity of visible light active TiO_2-x photocatalyst by introducing reduced graphene oxide via an eco-friendly and cost-effective hydrothermal method. This process facilitates graphene oxide reduction and incorporates intrinsic defects in TiO₂ lattice at a one-pot reaction process. The characteristic studies reveal that RGO/TiO_2-x nanocomposites were sufficiently durable and efficient for photocatalytic hydrogen generation under the visible light spectrum. The altered band gap of TiO_2-x rationally promotes the visible light absorption, and the RGO sheets present in the composites suppresses the electron-hole recombination, which accelerates the charge transfer. Hence, the noble metal-free RGO/TiO_2-x photocatalyst exhibited hydrogen production with a rate of 13.6 mmol h^?1g^?1_cat. under solar illumination. The appreciable photocatalytic hydrogen generation activity of 947.2 μmol h^?1g^?1_cat with 117 μAcm^?2 photocurrent density was observed under visible light (>450 nm).     

Vertically-heterostructured TiO2-Ag-rGO ternary nanocomposite constructed with {001} facetted TiO2 nanosheets for enhanced Pt-free hydrogen production

TiO₂ nanosheets with high ratio of {001} facets were coupled with reduced graphene oxide (rGO) nanosheets through the link of silver (Ag) nanoparticles, forming a novel ternary nanocomposite photocatalyst with a vertical heterostructure, TiO₂-Ag-rGO. The vertical anchoring of TiO₂-Ag nanosheets between rGO sheets was confirmed by transmission electron microscopy (TEM), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Due to excellent separation of electron-hole pairs in the TiO₂ nanosheets, enhanced electron transfer to rGO via Ag nanoparticles, the TiO₂-Ag-rGO nanocomposite exhibited an outstanding performance in photocatalytic hydrogen production, with a hydrogen production rate of 593.56 μmol g^?1 h^?1. This study provides new insights to the development of Pt-free photocatalysts for hydrogen production.     

Hydrogen production over the hetero-junction MnO2/SiO2

The motivation of this work is the hydrogen production as a non-polluting renewable energy under visible light. For this purpose, the hetero-junction 2%MnO₂/SiO₂ was synthetized by the impregnation method and characterized by X-ray diffraction, scanning electron microcopy (MEB), FTIR spectroscopy, diffuse reflectance and electrical conductivity. The X-ray analysis shows the amorphous silica substrate and the rutile phase MnO₂. The optical curve (αhν)² as a function of hν shows a direct transition of 1.83 eV for MnO₂. The capacitance measurement of the rutile indicates a flat band potential of ?0.027 V_SCE, more negative than the hydrogen evolution in SO₃^2? aqueous solution. As application, hydrogen was successfully evolved over the hetero-junction MnO₂/SiO₂. A good H₂ production was obtained after 30 min of irradiation corresponding to 5.1 mmol h^?1 g^?1 under visible light (29 mWcm^?2). The improved photocatalytic performance is due to the sensitizer MnO₂ homogeneously supported on porous SiO₂ substrate acting as templating agent.     

Highly efficient Bi2O3/MoS2 p-n heterojunction photocatalyst for H2 evolution from water splitting

The design of p-n heterojunction photocatalysts to overcome the drawbacks of low photocatalytic activity that results from the recombination of charge carriers and narrow photo-response range is promising technique for future energy. Here, we demonstrate the facile hydrothermal synthesis for the preparation of Bi₂O₃/MoS₂ p-n heterojunction photocatalysts with tunable loading amount of Bi₂O₃ (0–15 wt%). The structure, surface morphology, composition and optical properties of heterostructures were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–visible absorption spectroscopy, Brunauer-Emmett-Teller (BET) surface area, photoluminescence (PL), electrochemical impedance spectroscopy (EIS). Compare to pure Bi₂O₃ and MoS_2, the Bi₂O₃/MoS₂ heterostructures displayed significantly superior performance for photocatalytic hydrogen (H₂) production using visible photo-irradiation. The maximum performance for hydrogen evolution was achieved over Bi₂O₃/MoS₂ photocatalyst (10 μmol h⁻¹g⁻¹) with Bi₂O₃ content of 11 wt%, which was approximately ten times higher than pure Bi₂O₃ (1.1 μmol h⁻¹g⁻¹) and MoS₂ (1.2 μmol h⁻¹g⁻¹) photocatalyst. The superior performance was attributed to the robust light harvesting ability, enhanced charge carrier separation via gradual charge transferred pathway. Moreover, the increased efficiency of Bi₂O₃/MoS₂ heterostructure photocatalyst is discussed through proposed mechanism based on observed performance, band gap and band position calculations, PL and EIS data.     

Photocatalytic H2 production from glycerol–water mixtures over Ni/γ-Al2O3 and TiO2 composite systems

Ni/γ-Al₂O₃ prepared by impregnation, Ni/γ-Al₂O₃/CNT prepared in-situ during glycerol steam reforming, Ni/γ-Al₂O₃–TiO₂ and Ni/γ-Al₂O₃/CNT-TiO₂ were prepared by solid-state dispersion methods. These catalysts were characterized by XRD, SEM–EDAX, UV–Vis DRS, TEM, Raman and FT-IR techniques and were evaluated as photocatalysts for the production of H₂ using glycerol:water mixtures under solar light irradiation. For the first-time, higher rate of H₂ (3400 μmol h^?1 g^?1_cat) evolution was observed under the optimized conditions using Ni/γ-Al₂O₃/CNT-TiO₂ as a photocatalyst. This enhancement may be seen as due to the favorable absorption of solar light and the structural parameters minimizing the recombination of electron–hole pairs that resulted in improved activity of the catalyst. The present study clearly demonstrates that Ni/γ-Al₂O₃/CNT-TiO₂ as most promising photocatalyst for H₂ production from glycerol–water mixtures under solar light irradiation and through characterization, the structure–activity could be established.     

Facile synthesis of noble-metal free polygonal Zn2TiO4 nanostructures for highly efficient photocatalytic hydrogen evolution under solar light irradiation

Designing of noble-metal free and morphologically controlled advanced photocatalysts for photocatalytic water splitting using solar light is of huge interest today. In the present work, novel polygonal Zn₂TiO₄ (ZTO) nanostructures have been synthesized by citricacid assisted solid state method for the first time and synthesized nanostructures were characterized by using various techniques like PXRD, UV-Vis-DRS, PL, FT-IR, BET, FE-SEM and TEM for their structural, optical, chemical, surface and morphological properties. The PXRD and UV-Vis-DRS analysis show the existence of cubic and tetragonal phases. FE-SEM and TEM results confirm the formation of polygonal ZTO nanostructures. Synthesised ZTO nanostructures have been potentially applied for solar light-driven photocatalytic hydrogen evaluation from water splitting and compare the photocatalytic activity with synthesized conventional Zn₂TiO₄ and commercially available TiO₂, ZnO photocatalysts. A high rate of 529 μmolh^?1g^?1 solar light-driven photocatalytic H₂ evolution has been achieved by using a small amount (5 mg) of polygonal Zn₂TiO₄ nanostructures from glycerol-water solution. The enhanced photocatalytic performance of the polygonal Zn₂TiO₄ nanostructures compare to conventional Zn₂TiO₄ under solar light irradiation is due to the large surface area and low recombination rate. However having the same bandgap, the polygonal Zn₂TiO₄ nanostructures have shown enhanced photocatalytic performance than that of commercially available TiO₂, ZnO photocatalysts.