H2 Production Activity Research Articles

Anisotropic Charge Migration on Perovskite Oxysulfide for Boosting Photocatalytic Overall Water Splitting.

The synthesis of photocatalysts with both broad light absorption and efficient charge separation is significant for a high solar energy conversion, which still remains to be a challenge. Herein, a narrow-bandgap Y2Ti2O5S2 (YTOS) oxysulfide nanosheet coexposed with defined {101} and {001} facets synthesized by a flux-assisted solid-state reaction was revealed to display the character of an anisotropic charge migration. The selective photodeposition of cocatalysts demonstrated that the {101} and {001} surfaces of YTOS nanosheets were the reduction and oxidation regions during photocatalysis, respectively. Density functional theory (DFT) calculations indicated a band energy level difference between the {101} and {001} facets of YTOS, which contributes to the anisotropic charge migration between them. The exposed Ti atoms on the {101} surface and S atoms on the {001} surface were identified, respectively, as reducing and oxidizing centers of YTOS nanosheets. This anisotropic charge migration generated a built-in electric field between these two facets, quantified by spatially resolved surface photovoltage microscopy, the intensity of which was found to be highly correlated with photocatalytic H2 production activity of YTOS, especially exhibiting a high apparent quantum yield of 18.2% (420 nm) after on-site modification of a Pt@Au cocatalyst assisted by Na2S-Na2SO3 hole scavengers. In conjunction with an oxygen-production photocatalyst and a [Co(bpy)3]2+/3+ redox shuttle, the YTOS nanosheets achieved a solar-to-hydrogen conversion efficiency of 0.15% via a Z-scheme overall water splitting. Our work is the first to confirm anisotropic charge migration in a perovskite oxysulfide photocatalyst, which is crucial for enhancing charge separation and surface catalytic efficiency in this material.

Enhanced photocatalytic activity in H2 production from methanol aqueous solution based on the synthesized Pt-TiO2-decorated MoSe2 nanocomposites

In this work, a simple hydrothermal method to synthesize a ternary nanocomposite of Pt-TiO2 decorated on MoSe2 as a photocatalyst for hydrogen (H2) evolution from an aqueous methanol solution. The-as prepared Pt-TiO2/MoSe2 nanocomposite were characterized by XRD, Raman spectra, electron microscopy (FE-SEM/Mapping and HR-TEM), XPS UV-Vis and PL analysis. XRD patterns confirmed the presence of MoSe2 and Pt-TiO2 crystal phases in the Pt-TiO2/MoSe2 nanocomposite. Raman spectra displayed characteristic peaks corresponding to Mo-Se out-of-plane vibration and Pt-TiO2 vibration modes, confirming the successful synthesis of Pt-TiO2/MoSe2 nanocomposite. FE-SEM images showed a sheet-like morphology for MoSe2-NS and spherical Pt/TiO2 particles, with MoSe2 sparsely scattered on the Pt-TiO2 surface with EDS mapping confirmed even element distribution of Pt-TiO2/MoSe2 nanocomposite. TEM images revealed the transparent nature of MoSe2-NS with well-resolved lattice fringes. Pt-TiO2 exhibited uniform dispersion of Pt nanoparticles on TiO2, and the Pt-TiO2/MoSe2 nanocomposite showed integration of MoSe2-NS with Pt-TiO2. HRTEM images confirmed the lattice fringes of MoSe2-NS, Pt, and TiO2 particles. Tauc plot measurements revealed optical band gaps of 2.99 eV for MoSe2-NS, 3.19 eV for Pt-TiO2, and 2.78 eV for Pt-TiO2/MoSe2. XPS analysis confirmed the presence of Mo, Se, Pt, Ti, O, and C elements in the Pt-TiO2/MoSe2 nanocomposite. Based on the photoelectrochemical measurements, the Pt-TiO2/MoSe2 nanocomposite show the lower onset overpotential of 123 mV, which is much higher than Pt-TiO2 (179 mV) and MoSe2 (213 mV) at 10 mA/cm2. The photocatalytic efficiency of Pt-TiO2/MoSe2 nanocomposite in the context of H2 production through the enhancement of aqueous methanol under visible light exposure was assessed across different factors. Among these, the Pt-TiO2/MoSe2 nanocomposite exhibited the highest photoactivity in H2 production at 1337 μmolg−1 after 4 h. These results show the promising potential of the Pt-TiO2/MoSe2 nanocomposite catalyst in addressing both environmental and energy challenges in the future.

Reasonably design of hollow spherical g-C3N4/Mn0.25Cd0.75S heterojunction for efficient photocatalytic hydrogen production and tetracycline degradation

Developing efficient catalysts for photocatalytic hydrogen evolution and pollutant degradation is one of the most ideal methods to address energy and environmental pollution issues. To address the challenges of energy crisis and environmental issues, a hollow spherical g-C3N4/Mn0.25Cd0.75S (HCNS/MCS) heterostructure was constructed and characterized. The unique morphology and appropriate band gap of the hollow carbon nitride sphere (HCNS) make it a promising photocatalytic material. The growth of Mn0.25Cd0.75S solid solution on HCNS enhances the spatial separation of photo-generated charges at the HCNS/MCS interface, thereby promoting electron transfer and reaction kinetics. Under visible light irradiation, the HCNS/MCS exhibited the highest H2 production activity (31.34 mmol·g−1·h−1), which was 2.8 times that of pure MCS and 224 times that of pure HCNS. Moreover, the HCNS/MCS photocatalyst achieved a removal rate of 94% for tetracycline within 180 min under visible light, involving the •OH and •O2- radicals and following the proposed type-Ⅱ mechanism. This work contributes to the design of highly efficient photocatalytic materials with synergistic effects for photocatalytic hydrogen evolution and organic pollutant degradation.

Construction of NiS/MnCdS S-scheme heterojunction for efficient photocatalytic overall water splitting: Regulation of surface sulfur vacancy and energy band structure

The overall water splitting based on specific photocatalysts is one of the ultimate ways to solve the energy and environmental crisis facing humanity. Sulfide photocatalysts have greater potential in photocatalytic production of solar fuel. However, due to its easy photocorrosion phenomenon, it not effectively driving the water oxidation semi-reaction to produce oxygen, so how to use sulfide photocatalyst to decompose pure water to achieve stoichiometric reaction of H2/O2 production remains a quite challenging task. Herein, sulfur vacancies-rich MnCdS nanoparticles were modified with NiS nanosheets through the hydrothermal derivation method. Different concentration gradients of sulfur-vacancy in MnCdS nanoparticles (MnCdS-Vs-X) with tunable band structures were successful prepared by regulating the concentration of hydrazine hydrate, thus improves the efficiency of light energy utilization and charge separation and the existence of S defects was verified by transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR). The density function theory (DFT) calculation bears out that the draw into of S vacancy adjusted the band structure of MnCdS. Moreover, the successful construction of an S-scheme heterojunction between NiS and MnCdS-Vs-3 has been strongly demonstrated by in-situ XPS and UPS, which promoted interfacial charge separation and further improved the photocatalytic hydrogen evolution efficiency. The as-obtained S-scheme 20 %NiS/MnCdS-Vs-3 heterojunction exhibit excellent visible-light H2 production activity of 4099.55 μmol g−1h−1, 6.75 times higher than pure MnCdS. Most importantly, the excellent and stable photocatalytic overall water splitting activity of H2-509.70 μmol g-1h−1/O2-254.90 μmol g-1h−1 were obtained over 20 % NiS/MnCdS-Vs-3, which further demonstrates the application value of NiS/MnCdS-Vs-3 photocatalysts. This work proposes new ideas for the application of S-vacancies and S-scheme heterojunction in addressing the stability issues associated with sulfide-based photocatalysts in photocatalytic water splitting.

Effect of oxygen vacancies and crystal phases in defective Pt/ZrO2−x on its photocatalytic activity toward hydrogen production

Pt-deposited ZrO2−x with monoclinic or tetragonal were synthesized. More oxygen vacancies were created in Pt/tetragonal ZrO2−x, whereas higher photocatalytic activity in H2 production was obtained in Pt/monoclinic ZrO2−x.

Barium-induced lattice expansion of Ni(OH)2: enhancing catalytic urea oxidation activity for energy-saving H2 production.

Constructing an environmentally friendly and efficient electrocatalyst holds important and profound significance for energy-efficient hydrogen production. Replacing the oxygen evolution reaction with a lower potential urea oxidation reaction (UOR) may save energy in water electrolysis to produce hydrogen. The UOR is characterized by its high energy barrier, which results in slow reaction kinetics. In this study, we introduced Ba(OH)2 into Ni(OH)2 to form uniform nanosheets. Due to the introduction of Ba2+, the lattice expansion of Ni(OH)2 was triggered, leading to significant improvement in UOR activity. The catalyst achieved a current density of 100 mA cm-2 at only 1.316 V and exhibited remarkable stability over time. Density functional theory (DFT) calculations demonstrate that the Ba-Ni(OH)2 site significantly reduces the energy barrier for urea adsorption, intermediate steps, and desorption. This work provides a novel and environmentally friendly strategy for constructing energy-efficient and highly efficient catalysts through the doping of alkaline earth metals.

Thermal reflux to synthesise C3N4 nanostructures with high yield and enhanced photocatalytic activity in hydrogen evolution.

Graphitic carbon nitride (g-C3N4) is an attractive photocatalyst and a thermal reflux method was used to significantly increase the yield of g-C3N4 nanostructures and enhance their photocatalytic activity for H2 production. When raw material was placed in an inclined quartz tube with the bottom in the high temperature zone and the top in the low temperature zone, the vapor of the raw material was condensed from the top and refluxed to the bottom to then participate in the reaction again. This method can significantly improve the yield of g-C3N4 with an increase of 28.2%. When used as the photocatalyst in water splitting, these g-C3N4 nanostructures exhibit excellent activity with an H2 production of 2102 μmol h-1 g-1 under visible irradiation, which is 43.2% higher than the sample prepared by a traditional thermal polymerization method. This method is also promising to use for the synthesis of similar two-dimensional nanostructures for effective H2 production.

Heterointerface and crystallinity engineering of Ru/RuS2 dual co-catalysts for enhanced photocatalytic hydrogen evolution

In this paper, the Ru/RuS2 nanoparticles as dual co-catalysts were self-assembled on the surface of g-C3N4 nanotubes (Ru/RuS2/g-C3N4 NTs) for photocatalytic H2 production. The Ru/RuS2/g-C3N4 NTs showed greatly enhanced photocatalytic H2 production activity (1409 μmol·g−1·h−1), 1.16 times of RuS2/g-C3N4 NTs (1212 μmol·h−1·g−1), 10.51 times of Ru/g-C3N4 NTs (134 μmol·g−1·h−1), and 82.88 times of the pure g-C3N4 NTs (17 μmol·g−1·h−1). Besides, the apparent quantum yield value (AQE) of Ru/RuS2/g-C3N4 NTs is 3.92% at 370 nm. Ru/RuS2 as dual co-catalysts are self-assembled on the surface of g-C3N4 NTs and show strong electronic synergistic interaction between the interfaces, reduce ΔGH* of RuS2 and desorption energy of Ru, and promote the selectivity and activity of HER kinetically and thermodynamically respectively, which exhibits higher photogenerated carrier concentration and lower charge migration resistance than RuS2 and Ru, showing the synergistic effect to facilitate the generation and migration of carriers and provides active sites for photocatalysis.

A review on the recent advances in the design and structure–activity relationship of TiO2-based photocatalysts for solar hydrogen production

The recent progress in visible light driven photocatalysis by describing the integration of TiO2 with variety of materials, and how it helps in tailoring electronic, structural and optical properties towards improved solar H2 production activity.

Controlled synthesis of 2D-2D conductive metal-organic framework/g-C3N4 heterojunctions for efficient photocatalytic hydrogen evolution.

Designing photocatalysts with efficient charge separation and electron transport capabilities to achieve efficient visible-driven hydrogen production remains a challenge. Herein, 2D-2D conductive metal-organic framework/g-C3N4 heterojunctions were successfully prepared by an in situ assembly. Compared to pristine g-C3N4, the ratio-optimized Ni-CAT-1/g-C3N4 exhibits approximately 3.6 times higher visible-light H2 production activity, reaching 14 mmol g-1. Through investigations using time-resolved photoluminescence, surface photovoltage, and wavelength-dependent photocurrent action spectroscopies, it is determined that the improved photocatalytic performance is attributed to enhanced charge transfer and separation, specifically the efficient transfer of excited high-energy-level electrons from g-C3N4 to Ni-CAT in the heterojunctions. Furthermore, the high electrical conductivity of Ni-CAT enables rapid electron transport, contributing to the overall enhanced performance. This work provides a feasible strategy to construct efficient dimension-matched g-C3N4-based heterojunction photocatalysts with high-efficiency charge separation for solar-driven H2 production.

Facile fabrication of TT-T Nb2O5 heterophase junctions via in situ phase transformation towards enhanced photocatalytic H2-production activity

TT-T Nb2O5 heterophase junctions synthesized via a facile in situ phase transformation method showed much higher photocatalytic H2-production activity as compared with TT-Nb2O5 and T-Nb2O5 due to the oriented built-in electric field.

Titanium carbide (Ti3C2Tx) decorated molybdenum diselenide (MoSe2) nanoflower composite enhanced photo-electrocatalytic activity in hydrogen evolution

Two-dimensional titanium carbides (Ti3C2Tx) are part of the novel family of transition metal carbides/nitrides known as MXenes, which exhibit a broad range of photo-electrocatalytic applications. In this study, we present a facile hydrothermal synthesis method for Ti3C2Tx decorated on molybdenum diselenide (MoSe2) nanoflower composites, serving as an enhanced catalyst for hydrogen (H2) evolution. Ti3C2Tx, acting as a 2D conductive substrate, facilitates electron transfer, preventing MoSe2 agglomeration, while MoSe2 offers abundant active sites. The characterizations of surface analysis, optical properties, morphological nanostructure, and elemental composition performance of Ti3C2Tx nanosheets, MoSe2 nanoflowers, and Ti3C2Tx/MoSe2 nanoflower composites was conducted using FTIR, XRD, UV–Visible spectroscopy, SEM, EDS Mapping, TEM, and XPS techniques. The catalyst with optimal performance, the Ti3C2Tx/MoSe2 nanoflower composite demonstrates excellent functional properties in the H2 evolution, showing a lower overpotential of 135 mV and smaller Tafel slope of 72 mV/dec at 10 mA/cm2 compared to Ti3C2Tx nanosheets and MoSe2 nanoflowers. The Ti3C2Tx/MoSe2 nanoflower composite forms heterojunctions to inhibit the rapid recombination rate of photo-induced electrons and holes. In comparison to MoSe2 nanoflowers and Ti3C2Tx catalysts (where Tx = F, and O surface terminations), the optimized Ti3C2Tx/MoSe2 nanoflower composite exhibits significantly enhanced photocatalytic activity in H2 production, with a H2 production rate of 2146 μmolg−1h−1 superior than the Ti3C2Tx nanosheets (1367 μmolg−1h−1) and MoSe2 nanoflowers (986 μmolg−1h−1), respectively. Through this design, effective separation of photogenerated charge carriers is achieved, improving the activity of photocatalytic H2 production and demonstrating the promise of the cocatalyst strategy for photocatalysis.

Efficient photocatalytic green hydrogen production using crystalline elemental Boron nanostructures under visible light

Green Hydrogen emerges as a promising energy solution in the quest for achieving Net Zero goals. The application of particulate semiconductors in photocatalytic water splitting introduces a potentially scalable and economically viable technology for converting solar energy into hydrogen. Overcoming the challenge of efficiently transferring photoelectrons and photoholes for both reduction and oxidation on the same catalyst is a significant hurdle in photocatalysis. In this context, we introduce highly efficient crystalline elemental boron nanostructures as photocatalysts, employing a straightforward and scalable synthesis method yield green hydrogen production without the need for additional co-catalysts or sacrificial agents. The resulting photocatalyst demonstrates stability and high activity in H2 production, achieving over 1 % solar-to-hydrogen energy conversion efficiency (>15,000 μmol. g−1.h−1) during continuous 12-h illumination. This efficiency is credited to broad optical absorption and the crystalline nature of boron nanostructures, paving the way for potential scale-up of reactors using crystalline boron photocatalysts.

Exceptional piezocatalytic H2 production of nitrogen-doped TiO2@carbon nanosheets induced by engineered piezoelectricity

Piezocatalytic hydrogen evolution is a promising strategy to generate sustainable energy. In this report, nitrogen-doped (N-doped) TiO2@ carbon nanosheets (N-TiO2@C NSs) was successfully synthesized using C3N4 as a multifunctional template. During the synthesis, the two-dimensional (2D) architecture of C3N4 nanosheets directed the synthesis of TiO2 nanosheets. In addition, nitrogens of C3N4 were doped into the TiO2 lattice. Simultaneously, C3N4 was transformed into N-doped carbon nanosheets. N doping broke the crystal symmetry of TiO2, which endowed TiO2 with promising piezoelectric properties. The N-doped carbon nanosheets derived from C3N4 improved charge carrier separation efficiency and served as a flexible support to inhibit structural damage under sonication. Therefore, the N-TiO2@C NSs exhibited highly efficient activity for piezocatalytic H2 production (6.4 mmol·g−1·h−1) in the presence of methanol, much higher than those of the previously reported piezocatalysts. Our method is hoped to provide a new strategy for designing highly efficient piezocatalysts.

Cu(I)-4,4′-bipyridine coordination polymer for photocatalytic H2 generation

Solar water splitting represents one of the most promising strategies in the quest for clean and renewable energy. However, high cost, low conversion efficiency, large amount of sacrificial agents, and complex water splitting system limits its practical application. Herein, the previously reported earth-abundant Cu(I)-4,4′-bipyridine coordination polymer (denoted as Cu–BPY) has been investigated, which exhibits highly photocatalytic activity for H2 production (5275 μmol·g–1·h–1) with the relatively low amount of triethylamine (TEA) as sacrificial donor but without additional co-catalyst and photosensitizer. Moreover, DFT calculations establish the electronic structure of Cu(I)-4,4′-bipyridine with a narrow band gap of 2.39 eV, which is consistent with the experimental value of 2.21 eV. This finding provides a new experimental basis for designing water splitting and related photocatalytic materials.

Synergistic Enhancement of Photocatalytic H2 Evolution over NH2-MIL-125 Modified with Dual Cocatalyst.

The construction of efficient photocatalysts for water splitting to enable H2 evolution is pivotal to alleviate energy issues and environmental concerns. In this work, carbon dots (CDs) were prepared by employing "green solvent" ionic liquids as carbon sources and then combined with Pt/NH2-MIL-125, resulting in the emergence of a high-efficiency photocatalyst termed CDs-Pt/NH2-MIL-125 for the first time. This composite photocatalyst exhibited outstanding photocatalytic activity in H2 production under visible light irradiation. Notably, the H2 production rate of CDs100-Pt/NH2-MIL-125 reaches up to 951.4 μmol/g/h, which was 3.1 times that of Pt/NH2-MIL-125. The characterization results indicate that CDs and Pt uniformly dispersed on the surface of NH2-MIL-125 and fabricated a synergistic compact structure, providing a high BET surface area (985 m2 g-1) and a suitable band gap. Furthermore, the distinctive embeddable-dispersed CDs and Pt, as dual cocatalyst, can harvest light and facilitate the transfer of photogenerated electrons, thereby significantly augmenting the exploitation of visible light. The plausible mechanism of photocatalytic H2 evolution over the CDs-Pt/NH2-MIL-125 catalyst was also discussed. This work introduces a promising strategy for designing high-performance CDs-MOFs-based photocatalysts, an innovative step toward achieving efficient photocatalytic water splitting for H2 production.

Construction novel highly active photocatalytic H2 evolution over noble-metal-free trifunctional Cu3P/CdS nanosphere decorated g-C3N4 nanosheet

Hydrogen energy possesses immense potential in developing a green renewable energy system. However, a significant problem still exists in improving the photocatalytic H2 production activity of metal-free graphitic carbon nitride (g-C3N4) based photocatalysts. Here is a novel Cu3P/CdS/g-C3N4 ternary nanocomposite for increasing photocatalytic H2 evolution activity. In this study, systematic characterizations have been carried out using techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), Raman spectra, UV–Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), surface area analysis (BET), electrochemical impedance (EIS), and transient photocurrent response measurements. Surprisingly, the improved 3CP/Cd-6.25CN photocatalyst displays a high H2 evolution rate of 125721 μmol h−1 g−1. The value obtained exceeds pristine g-C3N4 and Cu3P/CdS by 339.8 and 7.6 times, respectively. This could be the maximum rate of hydrogen generation for a g–C3N4–based ternary nanocomposite ever seen when exposed to whole solar spectrum and visible light (λ > 420 nm). This research provides fresh perspectives on the rational manufacture of metal-free g-C3N4 based photocatalysts that will increase the conversion of solar energy. By reusing the used 3CP/Cd/g-C3N4 photocatalyst in five consecutive runs, the stability of the catalyst was investigated, and their individual activity in the H2 production activity was assessed. To comprehend the reaction mechanisms and emphasise the value of synergy between the three components, several comparison systems are built.

Investigation into the performance of Ag2O/g-C3N4 p-n heterojunction photocatalysts with efficient H2 production activity

The use of photocatalysts to break down water into hydrogen (H2) is one of the effective ways to solve energy scarcity and environmental pollution. The light utilization efficiency and separation efficiency of photogenerated carriers are key parameters for their application in photocatalytic H2 production. In this work, direct Z-scheme p-n heterojunction composites consisting of Ag2O and g-C3N4 (Ag2O/CN) were synthesized via an in-situ synthesis method. Characterizations of the synthesized Ag2O/CN composites were conducted to understand the performance of the photocatalysts for H2 production and to elucidate the possible mechanism. The experimental parameters such as Ag2O loading, sacrificial agent and electrolyte condition on photocatalytic H2 production were also investigated. The results show that the Ag2O/g-C3N4 composites have a favorable photoelectric effect and exhibit better H2 evolution performance than the single Ag2O and g-C3N4. The optimum formulation for the Ag2O/CN composites is to use triethanolamine as the sacrificial agent, 0.1 M KOH as the electrolyte, and 3 wt% Ag2O loading (3Ag2O/CN). The highest H2 production of 3Ag2O/CN is 7966.16 μmol/g/h, which is 3.68 and 195.48 times higher than that of g-C3N4 (2165.18 μmol/g/h) and Ag2O (40.75 μmol/g/h), respectively. The direct Z-scheme p-n heterojunction formed by g-C3N4 and Ag2O is the main reason for the enhanced photocatalytic activity. This study provides new ideas for the design of efficient g-C3N4-based p-n heterojunctions.

Fabrication of Co2RuS6/CdS Z-scheme heterojunction with sulfur vacancy for enhanced piezo-photocatalytic H2 evolution and in-depth analysis of charge-separation mechanism

The current photocatalytic hydrogen production performance is still limited by severe electron hole recombination. Notably, non-centrosymmetric piezoelectric materials could generate piezoelectric fields by mechanical forces to that promote the separation of photogenerated charges. Therefore, the combination of piezocatalysis and photocatalysis is expected to greatly promote the hydrogen production performance. In this work, a novel Z-type heterojunction Co2RuS6/CdS with sulfur vacancies (CRS/CdS-30) piezo-photocatalytic material was firstly primaried to boost H2 production activity. 10 % CRS/CdS-30 composite catalyst reached an impressive hydrogen production rate as 110.66 mmol·g−1·h−1 into combined effect of light and ultrasound, which was higher than the sum of pure photocatalytic (72.97 mmol·g−1·h−1) and pure piezoelectric performance (0.86 mmol·g−1·h−1). Moreover, H2 production rate for CRS/CdS-30 is 24, 14 and 15 times that of pure CdS, 10 % Co9S8/CdS-30 and 10 % RuS2/CdS-30, respectively. It has been confirmed through various characterization methods that: (1) The presence of sulfur vacancies greatly increases the catalytic active sites; (2) The transfer of photogenerated charges in the CRS/CdS-30 heterojunction follows the Z-scheme; (3) The piezoelectric field in CdS eliminates electrostatic shielding and tremendously enhances the separation efficiency of electron-hole pairs. This study supplies a new approach for constructing efficient piezo-photocatalytic materials.

Shape-Controlled Synthesis of Cu3TeO6 Nanoparticles with Photocatalytic Features.

Cu3TeO6 (CTO) has been synthesized by hydrothermal synthesis applying different pH values without any template or a calcination step to control the crystalline phase and the morphology of nanoparticles. The physicochemical properties characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, N2 adsorption, X-ray photoelectron spectroscopy, and diffuse reflectance ultraviolet-visible (DRUV-vis) spectroscopy techniques revealed that the pH values significantly influence the crystal growth. In acidic media (pH = 2), crystal growth has not been achieved. At pH = 4, the yield is low (10%), and the CTO presents irregular morphology. At pH = 6, the yield increases (up to 71%) obtaining an agglomeration of nanoparticles into spherical morphology. At basic conditions (pH = 8), the yield increases up to 90% and the morphology is the same as the sample obtained at pH = 6. At high basic conditions (pH = 10), the yield is similar (92%), although the morphology changes totally to dispersed nanoparticles. Importantly, the as-prepared CTO semiconductor presents photocatalytic activity for H2 production using triethanolamine as a sacrificial agent under visible light illumination. The results also revealed that the nanoparticles agglomerated in a spherical morphology with larger surface area presented almost double activities in H2 production compared to heterogeneously sized particles. These results highlight the suitable optoelectronic properties, including optical band gap, energy levels, and photoconductivity of CTO semiconductors for their use in photocatalytic H2 production.