Solvothermal synthesis,nanostructural characterization and gas cryo-adsorption studies in a metal–organic framework (IRMOF-1) material

A nanoporous metal–organic framework material, exhibiting an IRMOF-1 type crystalline structure, was prepared by following a direct solvothermal synthesis approach, using zinc nitrate and terephthalic acid as precursors and dimethylformamide as solvent, combined with supercritical CO₂ activation and vacuum outgassing procedures. A series of advanced characterization methods were employed, including scanning electron microscopy, Fourier-transform infrared radiation spectroscopy and X-ray diffraction, in order to study the morphology, surface chemistry and structure of the IRMOF-1 material directly upon its synthesis. Porosity properties, such as Brunauer–Emmet–Teller (BET) specific area (～520 m²/g) and micropore volume (～0.2 cm³/g), were calculated for the activated sample based on N₂ gas sorption data collected at 77 K. The H₂ storage performance was preliminary assessed by low-pressure (0–1 bar) H₂ gas adsorption and desorption measurements at 77 K. The activated IRMOF-1 material of this study demonstrated a fully reversible H₂ sorption behavior combined with an adequate gravimetric H₂ uptake relative to its BET specific area, thus achieving a value of ～1 wt.% under close-to-atmospheric pressure conditions.     

Effect of the acid type on clinoptilolite-rich tuff for hydrogen storage

Clinoptilolite from Gördes (Turkey) was treated with HCl, HNO₃ and H₂SO₄ solutions of varying concentrations (from 2.0 M to 6.0 M) at 90 °C for 4 h to evaluate its potential for possible applications in hydrogen storage. X-ray diffraction, X-ray fluorescence and nitrogen adsorption techniques were applied for characterization of the zeolites. Hydrogen adsorption capacities of clinoptilolite samples were found in the range between 1.609 and 2.391 mmol/g. The effects of the acid modification process on the structure and hence hydrogen adsorption was evaluated according to the obtained results.     

Screening and optimization of pretreatments in the preparation of sugarcane bagasse feedstock for biohydrogen production and process optimization

This work evaluated the effects of individual alkaline, sodium carbonate (Na₂CO₃ denoted as; NaC), sodium sulfide (Na₂SO₃ denoted as; NaS) and combination of NaC + NaS pretreatment for the saccharification of sugarcane bagasse (SCB). The effects of different pretreatments on chemical composition and structural complexity of SCB in relation with its saccharification were investigated. For enzymatic hydrolysis of pretreated SCB we have utilized the produced crude enzymes by Streptomyces sp. MDS to make the process more cost effective. A enzyme dose of 30 filter paperase (FPU) produced a maximum reducing sugar (RS) 592 mg/g with 80.2% hydrolysis yield from NaC + NaS pretreated SCB under optimized conditions. The resulted enzymatic hydrolysates of each pretreated SCB were applied for hydrogen production using Clostridium beijerinckii KCTC1785. NaC + NaS pretreated SCB hydrolysates exhibited maximum H₂ production relative to other pretreatment methods. Effects of temperature, initial pH of culture media and increasing NaC + NaS pretreated SCB enzymatic hydrolysates concentration (2.5–15 g/L) on bioH₂ production were investigated. Under the optimized conditions, the cumulative H₂ production, H₂ production rate, and H₂ yield were 1485 mL/L, 61.87 mL/L/h and 1.24 mmol H₂/mol of RS (0.733 mmol H₂/g of SCB), respectively. The efficient conversion of the SCB hydrolysate to H₂ without detoxification proves the viability of process for cost-effective hydrogen production.     

Modification of COF-108 via impregnation/functionalization and Li-doping for hydrogen storage at ambient temperature

Post-modification approaches such as Li-doping, impregnation, and functionalization are promising methods to enhance H₂ adsorption in metal–organic frameworks (MOFs) and covalent-organic frameworks (COFs). In this work, we propose a two-step method to modify COF-108 with the aim to enhance its hydrogen storage capacity at ambient temperature. First, we geometrically modified COF-108 through C₆₀ impregnation or aromatic ring grafting. Subsequently, we surface doped the modified COF-108 with Li atoms. COF-108 is the lightest 3D crystalline material ever reported and it is a promising H₂ storage material. Our grand canonical Monte Carlo (GCMC) simulations demonstrated that the combination of Li-doping with C₆₀ impregnation or aromatic ring grafting can potentially increase the volumetric H₂ adsorption capacity of COF-108 to reach a total H₂ adsorption capacity close to the U.S. DOE target. One of the Li-doped C₆₀-impregnated (Li₆C₆₀) COF-108 (with 8 Li₆C₆₀ moieties impregnated) showed an absolute H₂ uptake beyond the 2010 DOE target (45.6 mg/g and 28.6 g/cm³) at 233 K and 100 bar. Impregnation of C₆₀ and/or grafting of aromatic rings not only increased the density of doped Li in the modified COF-108 but also created more overlapped potential interaction with H₂, which resulted in higher number of H₂ adsorption sites per unit volume as compared to the unmodified material.     

Structural,electronic and spectral properties referring to hydrogen storage capacity in binary alloy ScBn (n = 1–12) clusters

Based on the DFT calculations within GGA approximation, we have systematically studied the ScB_n (n = 1–12) clusters and their hydrogen storage properties. The results show that the maximal adsorption for H₂ molecules is ScB₇ 6H₂ structure with the hydrogen storage mass fraction about 9.11%. For ScB_n·mH₂ clusters as n = 7 or 9–12, the average binding energies between 0.202 and 0.924 eV are suggestively conducive to hydrogen storage. In these medium clusters, the moderate adsorption strength can benefit application of hydrogen energy owning to easily adsorption and dissociation on H₂ molecules at room temperature and 1 bar pressure. Furthermore, the absorption spectrum is also investigated from TDDFT calculation. An obvious red-shift of spectral lines at 4.2 eV or 5.6 eV is detected with the increase of number of H₂ molecules. It can be regard as ‘fingerprint’ spectrum in experiment to indicate adsorption capacity of H₂ molecules for ScB_n·mH₂ nanostructures.     

Optimisation of sepiolite clay with phosphoric acid treatment as support material for CoB catalyst and application to produce hydrogen from the NaBH4 hydrolysis

Herein, the CoB catalyst supported on the sepiolite clay treated with phosphoric acid was utilized to produce hydrogen from the NaBH₄ hydrolysis. In order to analyse the performance of the phosphoric acid treated sepiolite clay supported-CoB catalyst, the NaBH₄ concentration effect, phosphoric acid concentration effect, phosphoric acid impregnation time effect, CoB catalyst percentage effect, and temperature effect were studied. In addition, XRD, XPS, SEM, TEM, BET, and FTIR analysis were performed for characterization of Co–B catalyst supported on the acid-treated sepiolite. The completion time of this hydrolysis reaction with Co–B (20%) catalyst supported on the sepiolite treated by 5 M phosphoric acid was approximately 80 min, whereas the completion time of this hydrolysis reaction with acid-free sepiolite-supported Co–B (20%) catalyst was approximately 260 min. There is a five-fold increase in the maximum production rate. The maximum hydrogen production rates of this hydrolysis reaction at 30 and 60 °C were found as 1486 and 5025 ml min⁻¹g⁻¹_catalyst, respectively. Activation energy was found as 21.4 kJ/mol. This result indicates that the acid treatment on sepiolite is quite successful. The re-usability of NaBH₄ hydrolysis reaction by CoB catalyst supported on sepiolite treated phosphoric acid for successive five cycles of NaBH₄ at 30 °C was investigated.     

Continuous hydrogen production from cofermentation of sugarcane vinasse and cheese whey in a thermophilic anaerobic fluidized bed reactor

The co-fermentation of vinasse and cheese whey (CW) was evaluated in this study by using two thermophilic (55° C) anaerobic fluidized bed reactors (AFBRs). In AFBR using vinasse and CW (AFBR-V-CW), the CW was added in increasing proportions (2, 4, 6, 8, and 10 g COD.L^?1) to vinasse (10 g COD.L^?1) to assess the advantage of adding CW to vinasse. By decreasing the hydraulic retention time (HRT) from 8 h to 1 h in AFBR-V, maximum hydrogen yield (HY), production rate (HPR), and H₂ content (H₂%) of 1.01 ± 0.06 mmol H₂.g COD^?1, 2.54 ± 0.39 L H₂.d^?1.L^?1, and 47.3 ± 2.9%, respectively, were observed at an HRT of 6 h. The increase in CW concentration to values over 2 g COD.L^?1 in AFBR-V-CW decreased the HY, PVH, and H₂%, with observed maximum values of 0.82 ± 0.07 mmol H₂.g COD^?1, 1.41 ± 0.24 L H₂.d^?1.L^?1, and 55.5 ± 3.7%, respectively, at an HRT of 8 h. The comparison of AFBR-V-CW and AFBR-V showed that the co-fermentation of vinasse with 2 g COD.L^?1 of CW increased the HPR, H₂%, and HY by 117%, 68%, and 82%, respectively.     

Tailored Ce- and Zr-doped Ni/hydrotalcite materials for superior sorption-enhanced steam methane reforming

Multi-functional hybrid materials are attractive for producing high-purity hydrogen (H₂) via catalytic steam reforming coupled with low temperature adsorptive separation of CO₂. In this work, modified Ni/hydrotalcite-like (HTlc) hybrid materials promoted with Ce and Zr species were synthesized and applied for the sorption-enhanced steam methane reforming process (or SESMR). The promotion with Ce and Zr resulted in strongly basic sites for CO₂ adsorption, and hence, improved H₂ production. Especially, the Ce-promoted hybrid material (Ce-HM1) exhibited the highest adsorption capacity (1.41 mol CO₂/kg sorbent), producing 97.1 mol% H₂ at T = 723 K, P = 0.1 MPa, S/C = 4.5 mol/mol and gas hourly space velocity or GHSV = 3600 mL/(g h); the breakthrough time was 1 h. High surface area and basicity of the promoted materials inhibited coke formation and undesired reactions. In addition to the improved catalytic activity and adsorption characteristics, these materials were stable and easily regenerable. Multi-cycle durability tests revealed that both the promoted materials Ce-HM1 and Zr-HM1 remained stable for up to 13 and 17 cycles. In contrast, the unpromoted hybrid material (HM1) was stable for 9 cycles only. Thus, promotion with Ce and Zr was beneficial for producing pure H₂.     

Adsorption of hydrogen isotopes in the zeolite NaX: Experiments and simulations

Among the different methods to separate hydrogen isotopes one is based on the physisorption at low temperature (below 100 K) where quantum effects induce a particular behavior. In the present work, we study the adsorption of single H₂ and D₂ on the zeolite NaX by combining experiments (manometry) from 30 to 150 K and molecular dynamics simulations at 40 and 77 K. Simulations also include the adsorption analysis for T₂. Adsorption on NaX membranes is simulated and quantum corrections are introduced by using the well-known Feynman–Hibbs approach into the interaction potentials. Experimental adsorption isotherms are reproduced by using the Toth equation and it is shown that the adsorption capacity increases with the molecular weight of the isotopes. Isosteric enthalpies evidence a heterogeneous adsorption process with two type of hydrogen isotopes differently linked to the zeolitic structure. The calculated pair distribution functions at high loadings exhibit a liquid-like structuration in the supercages of NaX, which may explain the different adsorption capacities for H₂, D₂ and T₂ and the heterogeneity of the adsorption process.     

Optimization of particle number,substrate concentration and temperature of batch immobilized reactor system for biohydrogen production by dark fermentation

Immobilized cell bioreactor was operated in batch mode for biohydrogen generation by dark fermentation from acid hydrolyzed waste wheat powder. It was aimed to optimize the fermentation conditions with the purpose of obtaining the highest hydrogen yield (Y_H2) and production rate (HPR) by applying Box–Wilson statistical experimental design method. Particle number (PN = 120–240; X₁), initial total sugar concentration (TS₀ = 10–30 g/l; X₂) and fermentation temperature (T = 35–55 °C; X₃) were selected as independent variables. Polyester fibers with particle diameter “Dp” = 0.5 cm were used as support material to immobilize microorganisms with heat-pretreated sludge. Quadratic equations for production yield and rate were developed by using experimental results. The maximum Y_H2 (3.21 mol H₂/mol glucose) and HPR (73.3 ml H₂/h) were predicted at the optimum conditions of PN = 240, TS₀ = 10 g/l and T = 44.9 °C. Also, analysis of variance, as well as sum of ranking difference test results demonstrated that fitting models were statistically significant.     

Evaluation of Bunsen reaction at elevated temperature and high pressure in continuous co-current reactor in iodine-sulfur thermochemical process

Bunsen reaction is one of the three reaction steps of iodine-sulfur process. In present study, Bunsen reaction is carried out in co-current reactor to identify effect of different operating conditions on concentrations of Bunsen reaction product mixture. Bunsen reaction studies have been done in tubular reactor, which is made of tantalum tube and stainless steel jacket, in 50–80 °C temperature range, 2–6 bar (g) pressure range. Feed flow rates are varied for HIx (mixture of hydroiodic acid, water and iodine) 1.2 l/h - 3 l/h, SO₂ 0.02 g/s – 0.24 g/s and O₂ 0.008 g/s ?0.016 g/s. It has been observed that, increasing SO₂ feed flow rate and pressure results in increased mole fraction of HI in HIx phase and H₂SO₄ in sulfuric acid phase. Increase in temperature increased the mole fraction of HI in HIx phase but decreased the mole fraction of H₂SO₄ in sulfuric acid phase. Increase in feed I₂/H₂O ratio and HIx feed flow rate, decreased the mole fraction of HI in HIx phase. Higher pressure improved the conversion of Bunsen reactants to products.     

In situ observation of H2 dissociation on the ZnO (0001) surface under high pressure of hydrogen using ambient-pressure XPS

The interaction of H₂ molecules with a ZnO (0001) single crystal surface has been studied over a wide pressure (10^?6–0.25 Torr) and temperature (300–600 K) range using ambient pressure X-ray photoelectron spectroscopy (AP-XPS). ZnO is well-known for interstitial hydrogen and hydrogen atoms in ZnO are believed to be incorporated by the dissociative adsorption of H₂ molecules in the atmosphere and their subsequent diffusion into the bulk. The dissociative adsorption of H₂ has been investigated at elevated pressures because H₂ molecules are not dissociated on the ZnO single crystal surface under ultrahigh vacuum (UHV) conditions. When the pressure is increased to several mTorr, the dissociative adsorption of H₂ takes place to form OH bonds on the surface. At 0.25 Torr, the ZnO surface is saturated with H atoms and the coverage is estimated to be 1.1 × 10¹⁵ atoms/cm² at 300 K. At higher surface temperatures, the equilibrium between the dissociative adsorption of gas-phase H₂ molecules and the associative desorption of surface H atoms is established. While maintaining the equilibrium, the surface has been monitored successfully in situ by utilizing AP-XPS.     

Selection of metabolic pathways for continuous hydrogen production under thermophilic and mesophilic temperature conditions in anaerobic fluidized bed reactors

This study evaluated the influence of hydraulic retention time (HRT) on hydrogen (H₂) production in anaerobic fluidized bed reactors at mesophilic (30 °C, AFBR-M) and thermophilic (55 °C, AFBR-T) temperatures. Reactors were fed sucrose-based synthetic wastewater (5000 mg chemical oxygen demand·L^?1) in the HRT of 8, 6, 4, 2, or 1 h. H₂ production rate increased from 67.8 ± 14.8 to 194.9 ± 57.0 ml H₂·h^?1 L^?1 (AFBR-T) and from 72.0 ± 10.0 to 344.4 ± 74.0 mL H₂·h^?1·l^?1 (AFBR-M) when HRT decreased from 8 to 1 h. Maximum H₂ yields for AFBR-T and AFBR-M were 1.93 ± 0.21 and 2.68 ± 0.48 mol H₂·mol^?1 sucrose, respectively. The main metabolites were acetic acid (31.3%–41.5%) and butyric acid (10.2%–20.7%) (AFBR-M) and acetate (20.1%–39.3%) and ethanol (14.3%–29.9%) (AFBR-T). Denaturing gradient gel electrophoresis profiles revealed selective enrichment of microbial populations responsible for H₂ production by the aceto-butyric route (AFBR-M) and ethanol-type fermentation (AFBR-T).     

Multiscale study of the structure and hydrogen storage capacity of an aluminum metal-organic framework

First-principles calculations based on density functional theory and Grand Canonical Monte Carlo (GCMC) simulations are carried out to study the structure of a new Aluminum Metal-Organic Framework, MOF-519, and the possibility of storing molecular hydrogen therein. The optimized structure of the inorganic secondary building unit (SBU) of MOF-519 formed by eight octahedrally coordinated aluminum atoms is presented. The different storage sites of H₂ inside the SBU and the BTB ligand are explored. Our results reveal that the SBU exhibits two different favorable physisorption sites with adsorption energies of ?12.2 kJ/mol and ?1.2 kJ/mol per hydrogen molecule. We have also shown that each phenyl group of BTB has three stable H₂ adsorption sites with adsorption energies between ?6.7 kJ/mol and ?11.37 kJ/mol. Using GCMC simulations; we calculated the molecular hydrogen (H₂) gravimetric and volumetric uptake for the SBU and MOF-519. At 77 K and 100 bar pressure, the hydrogen uptake capacity of SBU is considerably enhanced, reaching 16 wt.%. MOF-519 has a high gravimetric uptake, 10 wt.% at 77 K and 4.9 wt.% at 233 K. It has also a high volumetric capacity of 65 g/L at 77 K and 20.3 g/L at 233 K, indicating the potential of this MOF for hydrogen storage applications.     

Prolongation of H2 production during mixed carbon sources fermentation in E. coli batch cultures: New findings and role of different hydrogenases

Hydrogen (H₂) gas production in batch cultures was studied upon utilization of the mixture of glucose, glycerol and formic acid by Escherichia coli BW25113 wild type (wt) at pH of 5.5–7.5. At pH 7.5H₂ was continuously produced during 240 h but at pH 6.5 and 5.5 it was detected till 168 h and 120 h, respectively. Specific growth rate (μ) of wt was the highest (1.05 h^?1) at pH 6.5. Moreover, at pH 5.5 in hycE μ decreased by ～4.14 fold compared to wt, suggesting major role of Hyd-3 in cell growth. H₂ yield (8.8 mmol H₂ L^?1) was the highest at pH 7.5. In hybC H₂ yield was increased ～1.62 fold than in wt. These data might be applied for biomass and biohydrogen production from various organic wastes where mixtures of carbon sources are present.     

Effect of acid passivation and H2 sputtering pretreatments on the adhesive strength of sol–gel derived Hydroxyapatite coating on titanium surface

In this study, in order to increase the adhesive strength of a Hydroxyapatite (HA) coating, deposited on the surface of commercially pure titanium, acid passivation and hydrogen sputtering pretreatments were used. The pure titanium surfaces were passivized by acid solution and treated by hydrogen sputtering, at a temperature of 300 °C for 1 h. Ca(NO₃)₂·4H₂O and NH₄H₂PO₄ were chosen as starting precursors for Ca and P sources. HA coatings on the titanium surface were deposited using the sol–gel method and sintered in air at the temperatures of 750^oC-900 °C for 1 h. XRD, SEM, EDS and AFM analysis techniques were used for structural and morphological characterization. Scratch test was performed for determining the adhesion of HA coatings. The experimental results indicated that compact and crack free HA coating, which has a Ca/P ratio of 1:6, was formed on pure Titanium (Ti) surface. The adhesive strength values of the HA coating, pretreated with H₂ sputtering and acid passivation were found to be 72.84 MPa and 55.83 MPa at temperature of 900 °C, respectively. It was observed that H₂ plasma sputtering pretreatment, improved the adhesive strength of the HA coatings compared to pretreatment with acid passivation.     

The effect of oxygen–containing functional groups on the H2 adsorption of graphene–based nanomaterials: experiment and theory

The oxygen–containing functional groups of graphene oxide (GO) play an important role in hydrogen storage. In addition to the contribution of the specific surface area and micro–porous porosity, the interactions of the functional groups with H₂ molecules are also an important factor in the aspect of GO hydrogen storage. This paper explores the oxygen–containing functional groups affecting the hydrogen physisorption capacity of the GO and reduced graphene oxide (RGO) by experimental H₂ adsorption measurement and theoretical calculation. Experimental results related to synthesis of GO and RGO via the modified Hummer's method and characterized using SEM, TEM, SAED, XRD, FTIR, TGA and Raman spectroscopy, are presented. Compared with RGO, the surface and edge of GO contain a large amount of oxygen–containing functional groups and its specific surface area is slightly increased through BET measurement. GO is found to exhibit better H₂ uptake capacity (0.74 wt%) as compared to RGO (0.47 wt%) at 77 K and pressure up to 10 bars. The density functional theory is applied to optimize the adsorption configurations of H₂ on the surface of samples. Calculation results show that the adsorption on the GO can be promoted by surface functional groups epoxy, hydroxyl, carboxyl and carbonyl; the enhancement of hydroxyl is greater than other species on the surface and the maximal adsorption energy reaches to ?0.112 eV which is about twice that of graphene. As indicated above, these functional groups could be formed easily on the graphene surface, which not only enhance specific surface area and interlayer spacing, but also significantly change the location of carbons, redistributing the electron structure of graphene and enhancing the adsorption energy.     

Towards autothermal hydrogen production by sorption-enhanced water gas shift and methanol reforming: A thermodynamic analysis

Hydrogen production by the water gas shift reaction (WGS) is equilibrium limited. In the current study, we demonstrate that the overall efficiency of the WGS can be improved by co-feeding methanol and removing CO₂ in situ. The thermodynamics of the water gas shift and methanol reforming/WGS (methanol-to-shift, MtoS) reactions for H₂ production alone and with simultaneous CO₂ adsorption (sorption-enhanced, SEWGS and SEMtoS) were studied using a non-stoichiometric approach based on the minimisation of the Gibbs free energy. A typical composition of the effluent from a steam methane reformer was used for the shift section. The effects of temperature (450–750 K), pressure (5–30 barg), steam and methanol addition, fraction of CO₂ adsorption (0–95%) and energy efficiency of the shift systems have been investigated. Adding methanol to the feed facilitates autothermal operation of the shift unit, with and without CO₂ removal, and enhances significantly the amount of H₂ produced. For a set methanol and CO input, the MtoS and SEMtoS systems show a maximum productivity of H₂ between 523 and 593 K due to the increasing limitation of the exothermic shift reaction while the endothermic methanol steam reforming is no longer limited above 593 K. The heat of adsorption of CO₂ was found to make only a small difference to the H₂ production or the autothermal conditions.     

CO removal via selective methanation over the catalysts Ni/ZrO2 prepared with reduction by the wet H2-rich gas

The wet H₂-rich gas was used as reducing gas instead of the H₂/N₂ gas in the reduction step of the catalyst preparation. It is found that the selectivity for CO methanation over the catalysts 0.4Ni/ZrO₂ so-obtained was decreased in comparison to the case of the H₂/N₂ gas used as reducing gas. Even though, the samples with the different feed atomic ratios of Ni/Zr prepared by the impregnation method and the co-precipitation method, respectively, were evaluated with the wet H₂-rich gas both as reducing gas and as reactant gas. The catalysts Ni/ZrO₂-CP prepared by the co-precipitation method exhibited a high catalytic activity for CO removal at a lowered reaction temperature with increasing the Ni loading. Over the catalyst 3.0Ni/ZrO₂-CP, CO in the reactant gas could be removed to below 10 ppm at reaction temperatures of 220–260 °C with the selectivity higher than 50%. And the selectivity was kept at 100% during the 100 h test at 220 °C. The catalysts were characterized by XRD, XPS, XRF and the adsorption isotherm measurement. In addition, effect of water vapor in reactant gas was studied over the catalysts 0.4Ni/ZrO₂ with the wet H₂-rich gas and the dry H₂-rich gas as reactant gas, respectively, in the case of the H₂/N₂ gas fixed as reducing gas. It is seen that presence of water vapor in the reactant gas retarded methanation reactions of CO and CO₂ on the catalysts.     

Fabrication of anatase TiO2 tapered tetragonal nanorods with designed {100}, {001} and {101} facets for enhanced photocatalytic H2 evolution

In this study, anatase TiO₂ nanorods with exposed high-energy {100} and {001} facets and low-energy {101} facets were fabricated in the presence of surfactants cetyltrimethylammonium bromide, didecyldimethylammonium bromide, and ammonia via a facile hydrothermal method without the erosive reagent hydrofluoric acid. The particle size and morphology were mainly tuned by regulating the hydrothermal temperature. When the temperature was increased from 150 °C to 180 °C and 200 °C, the length of the nanorods decreased from 700-1000 nm to 400–500 nm and 100–200 nm, respectively. Concurrently, the edges and tops of the truncated tetragonal pyramid of the TiO₂ nanorods became blurry and flattened. The synthesized typical TiO₂ nanorods were then used as photocatalysts, and their performance during the direct generation of H₂ from water was evaluated. The TiO₂ nanorods obtained at 150 °C successfully produced high amounts of H₂ evolution (281.36 μmol) in the presence of methanol as a sacrificial agent under ultraviolet light irradiation for 4 h. The outstanding photocatalytic activity of the nanorods was mainly ascribed to the formation of surface heterojunctions in the edges and corners between adjacent high-energy {001} or {100} facets and low-energy {101} facets. The formed heterojunctions could facilitate charge separation through preferential carrier flow toward the specific facets.