Surface modification of semiconductor photoelectrode for improved solar cell performance

The investigation is focused on the synthesis of nanostructured TiO₂–CuO admixed photoelectrode and its use as a photoelectrode of high-efficiency PEC solar cells for hydrogen production. TiO₂, in the nanostructured form, has been prepared by hydrolysis of titanium(IV) isopropoxide solution. An improvement in the nanostructured TiO₂ photoelectrode carried out in the present work corresponds to admixing CuO to improve the spectral response. In the present study, photo-electrochemical (PEC) and hydrogen evolution characteristics of new types of ns-TiO₂–CuO admixed/Ti septum-based semiconductor septum photo-electrochemical (SC-SEP PEC) solar cell has been studied. The CuO admixed ns-TiO₂ exhibited a high photocurrent and photovoltage of 18.6 mA/cm² and 680 mV, respectively. The ns-TiO₂–CuO electrode exhibited a higher hydrogen gas evolution rate of 14.00 l/h m².     

MoS2 supported on hydrogenated TiO2 heterostructure film as photocathode for photoelectrochemical hydrogen production

The substitution of noble metal platinum catalyst is one of the important research contents for sustainable development and is also the key to the practical application of photoelectrochemical (PEC) hydrogen production. In this work, we loaded the 1T-2H mixed phase MoS₂ on the hydrogenated anatase/rutile heterophase TiO₂ (A-H-RTNA) by hydrothermal method to prepare a new MoS₂/A-H-RTNA electrode material. The prepared material exhibited higher carrier density, lower PL intensity and higher conductivity than Pt/A-H-RTNA because 1T-MoS₂ has more active sites and lower charge transfer resistance than Pt. With the bias voltage of −0.4 V, the optimized 16MoS₂/A-H-RTNA as photocathode shows the largest PEC hydrogen production rate of 1840 mmol m⁻² h⁻¹, which is 2.9 and 2.2 times higher than those of A-H-RTNA (625 mmol m⁻² h⁻¹) and Pt/A-H-RTNA (848 mmol m⁻² h⁻¹), respectively. We innovatively used the prepared 16MoS₂/A-H-RTNA film as counter electrode instead of Pt electrode to construct a PEC system without any noble-metal. The result demonstrates that the noble-metal-free MoS₂ loaded on TiO₂ electrode as counter electrode has 75% PEC activity of noble metal Pt electrode. This study develops a PEC method for hydrogen evolution, which no longer depends on precious metal platinum as cathode.     

Reorganization of a photosensitive carbo-benzene layer in a triptych nanocatalyst with enhancement of the photocatalytic hydrogen production from water

The preparation of a triptych nanomaterial made of TiO₂ nanoparticles as semiconductor, Ag plasmonic nanoparticles and a carbo-benzene macrocyclic molecule as photosensitizer is described, and used to produce hydrogen by photo-reduction of pure deionized water under 2.2 bar argon pressure without any electrical input. Silver nanoparticles (~5 nm) are grafted onto the surface of commercial TiO₂ nanoparticles (~23 nm) by a photo-deposition process using an original silver amidinate precursor. The thickness of the photosensitive layer (2 nm), which completes the assembly, plays a crucial role in the efficiency and robustness of the triptych nanocatalyst. Thanks to the organic layer reorganization during the first ~24 h of irradiation, it leads to an enhancement of the hydrogen production rate up to 5 times. The amount of silver and carbo-benzene are optimized, along with the mass concentration of nanocatalyst in water and the pH of the aqueous medium, to allow reaching a hydrogen production rate of 22.1 μmol·h⁻¹·g_{photocatalyst}⁻¹.     

TiO2/CeO2 core/shell heterojunction nanoarrays for highly efficient photoelectrochemical water splitting

In this paper, novel TiO₂/CeO₂ core/shell heterojunction nanorod (NR) arrays were synthesized as photoanode for photoelectrochemical (PEC) water splitting via a simple and facial two-step hydrothermal approach. This synthesis route can obtain different amount of CeO₂ nanoparticles by controlling the hydrothermal time and eventually achieve uniform TiO₂/CeO₂ core/shell nanostructures. The uniform TiO₂/CeO₂ core/shell heterojunction nanoarrays exhibit a markedly enhanced photocurrent density of 5.30 mA·cm^?2 compared to that of pristine TiO₂ NR 1.79 mA·cm^?2 at 1.23 V vs. RHE in 1 M KOH solution. The superior PEC performance of the TiO₂/CeO₂ core/shell heterojunction is primarily due to much enhanced visible light absorption and appropriate gradient energy gap structure. This work not only offers the synthesis route for the novel TiO₂/CeO₂ core/shell heterojunction, but also suggests that this new core/shell heterojunction has a great potential application for efficient PEC water splitting devices.     

Investigation of the annealing treatment on the performance of TiO2 photoanode

Developing low-cost semiconductor photoanode toward efficient and stable oxygen evolution reaction (OER) is highly desirable for photoelectrochemical (PEC) water splitting. Herein, nanoparticulate titanium dioxide (TiO₂) electrodes were prepared using Degussa P25 powders by spin-coating method. The effects of annealing conditions on the PEC performance of the nanoparticulate TiO₂ photoanode was systematically investigated including temperature, annealing time and atmosphere. The results demonstrate that the TiO₂/fluorine-doped tin oxide substrates (FTO/TiO₂) electrode annealed at argon (Ar) atmosphere under 450 °C shows the highest PEC performance. The photocurrent density of FTO/TiO₂ annealed in Ar for only 0.5 h reached to 120 μA/cm² at 0.3 V vs. Hg/HgO which is about 10 times higher than that of the unannealed one. The X-ray photoelectron spectroscopy (XPS) results show the thermal treatment can produce oxygen vacancies on the surface of TiO₂ which reduce the recombination of photogenerated electron-hole pairs and expanding the visible light absorption by introducing defective energy levels. The electrochemical impedance spectroscopy (EIS) approves that appropriate annealing treatment can effectively enhance the electron conductivity resulting in low charge transfer resistance. All these factors contribute to improving the PEC activity of TiO₂ photoanode.     

Non-precious metal MoO2 co-catalysts efficiently enhance hydrogen production of ZnIn2S4 under visible light

Photogenerated electron-hole separation and transfer and band gap modulation are the main reasons for the performance of semiconductor catalysts. These problems can be effectively solved by the proper use of co-catalysts. However, the current co-catalysts are generally noble metal co-catalysts, which cannot be used industrially because of their high cost. Therefore, it is important to use non-noble metal co-catalyst to solve these problems. In this study, MoO₂ with localized surface plasmon resonance (LSPR) effect loaded onto ZnIn₂S₄ (ZIS) by primary hydrothermal method and structured to form type II heterojunctions. The formation of the heterojunctions not only tunes the band gap to improve the light absorption intensity, but also reduces the charge transfer resistance and promotes electron-hole directed movement to improve the electron-hole separation efficiency. The tuning of the band gap and the increase in the electron-hole separation rate lead to improved performance of all ZIS/MoO₂ heterojunctions under visible light (λ ≥ 420 nm). Among them, ZIS/MoO₂-4% has the best photocatalytic performance of 2.757 mmol g^?1 h^?1, which is 3.75 times higher than that of pure ZIS (0.736 mmol g^?1 h^?1). This study provides a new strategy for the preparation of high performance catalysts without precious metals.     

Tuning of electrocatalytic activity of WO3–TiO2 nanocomposite electrode for alkaline hydrogen evolution reaction

The study reports the synthesis of mesoporous WO₃–TiO₂ nanocomposite with tuned particle size (~7 nm), pore diameter (~4.9 nm), specific surface area (S_BET = 129.112 m²/g) and pore volume (V_tot = 0.185 cm³/g) by an acid catalyzed peptization method, and its utilization for the development of stable catalytic electrode with enhanced activity towards alkaline hydrogen evolution reaction (HER). The SEM and AFM analyses confirm the formation of good quality composite electrodes with improved surface roughness through electroless deposition method. The developed WO₃–TiO₂ nanocomposite electrode exhibits low overpotential value of 120 mV with an exchange current density of 6.20 × 10^?5 mA/cm², and a low Tafel slope value of 98 mV/dec. Apart from the high HER performance, the developed WO₃–TiO₂ nanocomposite electrode exhibits competency with the state-of-the-art electrode materials for alkaline HER in industrial processes with sustained catalytic activity, tolerance behavior and long-term stability.     

In2O3:Sn/TiO2/CdS heterojunction nanowire array photoanode in photoelectrochemical cells

The design of photoanode with highly efficient light harvesting and charge collection properties is important in photoelectrochemical (PEC) cell performance for hydrogen production. Here, we report the hierarchical In₂O₃:Sn/TiO₂/CdS heterojunction nanowire array photoanode (ITO/TiO₂/CdS-nanowire array photoanode) as it provides a short travel distance for charge carrier and long light absorption pathway by scattering effect. In addition, optical properties and device performance of the ITO/TiO₂/CdS-nanowire array photoanode were compared with the TiO₂ nanoparticle/CdS photoanode. The photocatalytic properties for water splitting were measured in the presence of sacrificial agent such as SO₃²⁻ and S²⁻ ions. Under illumination (AM 1.5G, 100 mW/cm²), ITO/TiO₂/CdS-nanowire array photoanode exhibits a photocurrent density of 8.36 mA/cm² at 0 V versus Ag/AgCl, which is four times higher than the TiO₂ nanoparticle/CdS photoanode. The maximum applied bias photon-to-current efficiency for the ITO/TiO₂/CdS-nanowire array and the TiO₂ nanoparticle/CdS photoanode were 3.33% and 2.09%, respectively. The improved light harvesting and the charge collection properties due to the increased light absorption pathway and reduced electron travel distance by ITO nanowire lead to enhancement of PEC performance.     

First demonstration of photoelectrochemical water splitting by commercial W–Cu powder metallurgy parts converted to highly porous 3D WO3/W skeletons

Hydrogen evolution through photoelectrochemical (PEC) water splitting by tungsten oxide-based photoanodes, as a stable and environmental-friendly material with moderate band gap, has attracted significant interest in recent years. The performance of WO₃ photoanode could be hindered by its poor oxygen evolution reaction kinetics and high charge carrier recombination rate. Additionally, scalable and cost-effective commercial procedure to prepare nanostructured electrodes is still challenging. We present, for the first time, a novel and scalable method to fabricate highly efficient self-supported WO₃/W nanostructured photoanodes from commercial W–Cu powder metallurgy (P/M) parts for water splitting. The electrodes were prepared by electrochemical etching of Cu networks followed by hydrothermal growth of WO₃ nanoflakes. Interconnected channels of W skeleton provided high active surface area for the growth of WO₃ nanoflakes with a thickness of ~40 nm and lateral dimension of ~250 nm. The optimized photoelectrode having 35% interconnected porosity exhibited an impressive current density of 4.36 mA cm⁻² comprising a remarkable photocurrent of 1.71 mA cm⁻² at 1.23 V vs. RHE under 100 mW cm⁻² simulated sunlight. This achievement is amongst the highest reported photocurrents for WO₃ photoelectrodes with tungsten substrate reported so far. Impedance and Mott-Schottky analyses evidenced fast charge transfer, low recombination rate, and accelerated O₂ detachment provided by optimum 3D porous WO₃/W electrode. Due to the nature of the commercial P/M parts and low-temperature hydrothermal processing, the procedure is cost-effective and scalable which can pave a new route for the fabrication of highly porous and efficient water splitting electrodes.     

In-situ construction of direct Z-scheme sea-urchin-like ZnS/SnO2 heterojunctions for boosted photocatalytic hydrogen production

Constructing direct Z-scheme heterostructure is an effective way to promote the separation of photogenerated carriers and optimize the redox ability of the photocatalytic system. This work reports the in-situ synthesis of sea-urchin-like ZnS/SnO₂ Z-scheme heterojunctions via a one-step hydrothermal method. Both experimental results and density functional theory (DFT) calculations indicate that the tight interfaces derived from in-situ precursor dissociation can ensure a fast transfer for photogenerated carriers, meanwhile, the Z-scheme type of heterojunctions can increase the carrier separation efficiency and maintain the high reduction ability of photogenerated electrons. As expected, the photocatalytic hydrogen evolution rate of the as-optimized ZnS/SnO₂ sample can reach 2.17 mmol g^?1 h^?1, which is 15.5 times higher than that of the commercial ZnS. This work can offer a novel strategy for designing Z-scheme heterojunction as well as controlling the contact interface for boosted photocatalytic activity.     

Biomass-derived hierarchical porous CdS/M/TiO2 (M = Au,Ag, pt,pd) ternary heterojunctions for photocatalytic hydrogen evolution

We demonstrate a general method for the synthesis of biomass-derived hierarchical porous CdS/M/TiO₂ (M = Au, Ag, Pt, Pd) ternary heterojunctions for efficient photocatalytic hydrogen evolution. A typical biomass—wood are used as the raw sources while five species of wood (Fir, Ash, White Pine, Lauan and Shiraki) are chosen as templates for the synthesis of hierarchical porous TiO₂. The as-obtained products inherited the hierarchical porous features with pores ranging from micrometers to nanometers, with improved photocatalytic hydrogen evolution activity than non-templated counterparts. Noble metals M (M = Pt, Au, Ag, Pd) and CdS are loaded via a two-step photodeposition method to form core (metal)/shell (CdS) structures. The photocatalytic modules—CdS(shell)/metal (core)/TiO₂ heterostructures, have demonstrated to increase visible light harvesting significantly and to increase the photocatalytic hydrogen evolution activity. The H₂ evolution rates of CdS/Pd/TiO₂ ternary heterostructures are about 6.7 times of CdS/TiO₂ binary heterojunctions and 4 times higher than Pd/CdS/TiO₂ due to the vertical electron transfer process. The design of such system is beneficial for enhanced activity from morphology control and composition adjustment, which would provide some new pathways for the design of promising photocatalytic systems for enhanced performance.     

Simultaneously efficient light absorption and charge transport of CdS/TiO2 nanotube array toward improved photoelectrochemical performance

CdS has been widely used to modify TiO₂-based photoanodes for photoelectrochemical (PEC) water splitting. Due to the poor interface contact between chalcogenides and oxides, however, such CdS modified TiO₂ materials usually exhibit inefficient separation and transport of charges, leading to an unsatisfactory efficiency during the PEC water splitting process. Addressing this issue, we herein report a CdS/TiO₂ nanotube array (CdS/TNA) photoanode that was fabricated through a successive ion layer absorption and reaction (SILAR) method with an additional subsequent annealing. This post-annealing process is essential to enhance the interface contact between the CdS and the TNAs, resulting in an accelerated transfer of photogenerated electrons from the CdS to the TNAs. In addition, the post-annealing also improves the light absorption capability of the CdS/TNA photoanode. The simultaneous enhancement of charge transport and light absorption provided by the post-annealing is essential for improving the PEC performance of the CdS/TNA photoanode. The CdS/TNA photoanode obtained by this strategy exhibits a much enhanced PEC performance in water splitting, and its photocurrent density and solar-to-hydrogen conversion efficiency could reach 4.56 mA cm⁻² at 1.23 V vs. reversible hydrogen electrode and 5.61%, respectively. This simple but effective route can provide a general strategy for obtaining high-performance oxide-based photoelectrodes.     

Improved photon management in a photoelectrochemical cell with Nd-modified TiO2 thin film photoanode

Photon management involving particularly an up-conversion process is proposed as a relatively novel strategy for improving the efficiency of hydrogen generation in photoelectrochemical cells (PEC) with wide-band gap photoanodes. Optically active photoanode has been constructed by electrodeposition of titanium dioxide nanopowders containing Nd³⁺ ions, synthesized via a sol-gel method, onto ITO/TiO₂(thin film) substrates. Thin films of TiO₂ have been deposited by means of RF magnetron sputtering in an ultra-high-vacuum system. X-ray diffraction, scanning electron microscopy, UV-VIS-NIR spectrophotometry, and photoluminescence have been applied to assess the properties of photoanodes. In experiments involving photon-assisted water splitting, an external up-converter containing Yb³⁺/Er³⁺ rare-earth ions has been used. Photocurrent as a function of voltage (V_B) under illumination with white light is relatively high (280 μA at V_B = 0 V) for pure TiO₂ thin films and it is not affected by the electrodeposition of TiO₂:Nd³⁺ powders. NIR-driven up-conversion with laser excitation at λ = 980 nm has been found responsible for a 13-fold increase in photocurrent at V_B = 0 V in the modified PEC configuration.     

Enhancing hydrogen evolution of water splitting under solar spectra using Au/TiO2 heterojunction photocatalysts

An effective improvement of hydrogen evolution from water splitting under solar light irradiation was investigated using quantum dots (QDs) compounds loaded onto a Au/TiO₂ photocatalyst. First, Au/TiO₂ was prepared by the deposition-precipitation method, and then sulfide QDs were loaded onto the as-prepared Au/TiO₂ by a hydrothermal method. QDs were loaded onto Au/TiO₂ to enhance the energy capture of visible light and near-infrared light of the solar spectrum. The results indicated that the as-prepared heterojunction photocatalysts absorbed the energy from the range of ultraviolet light to the near-infrared light region and effectively reduced the electron-hole pair recombination during the photocatalytic reaction. Using a hydrothermal temperature of 120 °C, the as-prepared (ZnS–PbS)/Au/TiO₂ photocatalyst had a PbS QDs particle size of 5 nm, exhibited an energy gap of 0.92 eV, and demonstrated the best hydrogen production rate. Additionally, after adding 20 wt % methanol as a sacrificial reagent to photocatalyze for 5 h, the hydrogen production rate reached 5011 μmol g⁻¹ h⁻¹.     

A novel photoelectrochemical cell with self-organized TiO2 nanotubes as photoanodes for hydrogen generation

A photoelectrochemical (PEC) cell with an innovative design for hydrogen generation via photoelectrocatalytic water splitting is proposed and investigated. It consisted of a TiO₂ nanotube photoanode, a Pt/C cathode and a commercial asbestos diaphragm. The PEC could generate hydrogen under ultraviolet (UV) light-excitation with applied bias in KOH solution. The Ti mesh was used as the substrate to synthesize the self-organized TiO₂ nanotubular array layers. The effect of the morphology of the nanotubular array layers on the photovoltaic performances was investigated. When TiO₂ photocatalyst was irradiated with UV-excitation, it prompted the water splitting under applied bias (0.6 V vs. Normal Hydrogen Electrode, NHE.). Photocurrent generation of 0.58 mA/cm² under UV-light irradiation showed good performance on hydrogen production.     

Structural properties of CuO/TiO2 nanorod in relation to their catalytic activity for simultaneous hydrogen production under solar light

CuO was introduced into porous TiO₂ nanorod through impregnation method. Before the impregnation step, TiO₂ nanorod was hydrothermally synthesized from TiO₂ powder in aqueous NaOH solution and followed by thermal treatment at 450 °C. The structures and properties of impregnated samples were characterized using various techniques, including XRD, BET, XAS, TEM, and UV-DRS. Their photocatalytic performance on simultaneous hydrogen production from pure water and aqueous methanol solution was also investigated under solar light. It was found that CuO/TiO₂ nanorod possessed a high surface area, good photocatalytic property and excellent hydrogen generation activity. Incorporation of Cu ions into the lattice framework of anatase TiO₂ nanorod enhanced the efficiency in visible region at 438–730 nm. Moreover, the XAS results showed that some Cu ions formed solid solution in the TiO₂ nanorod (Cu_xT_1−xO₂). However, the excessive incorporation of Cu ions did not improve any ability of anatase TiO₂ nanorod for production of hydrogen from pure water splitting. This could be due to the excessive CuO agglomeration at outside-pores which blocked the sensitization of TiO₂ nanorod. Only 1% Cu/TiO₂ nanorod was found to be a remarkable and an efficient photocatalyst for hydrogen production under solar light from both pure water and sacrificial methanol splitting. The highest rate of hydrogen production of 139.03 μmol h⁻¹ g_catalyst⁻¹ was found in sacrificial methanol which was 3.24% higher than in pure water.     

Enhanced photoelectrochemical water splitting using zinc selenide/graphitic carbon nitride type-II heterojunction interface

The objective of this research is to construct a type-II heterojunction interface for effective photoelectrochemical (PEC) water splitting for hydrogen generation. A series of ZnSe/g-C₃N₄ heterojunctions is prepared by ultrasonication procedure and tested for PEC water splitting for the first time. The successful formation of ZnSe/g-C₃N₄ is confirmed by phase, morphological and optical analysis. Linear sweep voltammetry of 0.05 ZG (0.05% ZnSe/g-C₃N₄) showed a six-fold higher photocurrent density of 500 μA than g-C₃N₄. These results are supported by the Tafel slopes and PL (photoluminescence spectroscopy) studies by showing the smallest slope and lesser electron-hole recombination for 0.05 ZG. Increased lifetime of 107 ms and a higher donor density of 3.6 × 10¹⁹ cm^?3 for 0.05 ZG is observed. The smallest semicircle for 0.05 ZG in EIS implies the least charge transfer resistance among the prepared heterojunctions. All the results comply with each other showing the successful formation of type-II heterojunction for enhanced PEC water splitting.     

Enhanced hydrogen generation via overall water splitting using novel MoS2-BN nanoflowers assembled TiO2 ternary heterostructures

Envisaging headway in the applicability of sustainable H₂ energy, the novel report of the fabrication of MoS₂-BN/TiO₂ (MBT) heterogeneous nanostructures has been proposed via facile in-situ hydrothermal route with an aim to propound the superior substitute of noble metal based conventionally employed catalytic system to surmount their exorbitant cost. We inferred the ascendancy of MoS₂-BN nanoflowers over pristine MoS₂ counterpart in an establishment of TiO₂ based heterostructured catalysis. MBT heterostrucutres were extensively scrutinized with respect to their structural, optoelectronic and computational characteristics. En route to enhanced H₂ evolution, we have investigated the significance of interfacial junctions and exposed sites in the MBT heterostructures. In order to achieve broader pertinence in green H₂ fuel, the performance of MBT heterostrucutres was ascertained with subject to photochemical, electrochemical and photo-electrochemical (PEC) water splitting. Loaded concentration of MoS₂-BN was varied in MBT catalysts and 2.5 wt% MoS₂-BN/TiO₂ exhibited optimum photocatalytic response with an H₂ production rate of 2.6 mmol/g/h with 6.94% AQY and improved photo-current response of 0.99 mA/cm² towards PEC. Electrochemical investigations further intensified the caliber of MBT as HER catalyst ascribed to the higher cathodic current density of 49.23 mA/cm² at 1.22 V potential. The advancement in the catalytic efficiency of MBT heterostructures was evidenced by the synergetic relationship between MoS₂-BN and TiO₂ which stimulated the separation and transfer of photo-charged carriers, and lowered the overpotential values consequently surging the kinetics of H₂ evolution.     

Photoelectrochemical water splitting on highly smooth and ordered TiO2 nanotube arrays for hydrogen generation

To improve the photoelectrochemical (PEC) water splitting efficiency for hydrogen production, we reported the fabrication of lotus-root-shaped, highly smooth and ordered TiO₂ nanotube arrays (TiO₂ NTs) by a simple and effective two-step anodization method. The TiO₂ NTs prepared in the two-step anodization process (2-step TiO₂ NTs) showed better surface smoothness and tube orderliness than those of TiO₂ NTs prepared in one-step anodization process (1-step TiO₂ NTs). Under illumination of 100 mW/cm² (AM 1.5, simulated solar light) in 1 M KOH solution, water was oxidized on the 2-step TiO₂ NTs electrode with higher efficiency (incident-photon-to-current efficiency of 43.4% at 360 nm and photocurrent density of 0.90 mA/cm² at 1.23 V_RHE) than that on the 1-step TiO₂ NTs electrode. The effective photon-to-hydrogen conversion efficiency was found to be 0.18% and 0.49% for 1-step TiO₂ NTs and 2-step TiO₂ NTs, respectively. These results suggested that the structural smoothness and orderliness of TiO₂ NTs played an important role in improving the PEC water splitting application for hydrogen generation.     

Carbon nitride quantum dots (CNQDs)/TiO2 nanoparticle heterojunction photocatalysts for enhanced ultraviolet-visible-light-driven bisphenol a degradation and H2 production

The extension of the absorption band of solar energy is an efficient strategy to dramatically enhance the application value of TiO₂. Based on this, we have prepared carbon nitride quantum dots (CNQDs)/TiO₂ nanoparticle heterojunctions by mixing TiO₂ and the as-prepared CNQDs by the simple mechanical stirring method. The synthesized CNQDs-x/TiO₂ composites were systematically characterized in term of their physicochemical properties, the performance of photocatalytic degradation of Bisphenol A, and their photocatalytic hydrogen evolution performance under stimulated sunlight. The CNQDs/TiO₂ nanoparticle exhibited a lattice spacing of 0.352 nm, assigning to the (101) crystal plane of anatase phase TiO_2. Intriguingly, the modification of TiO₂ nanoparticle with CNQDs can indeed get a narrower optical band gap of 3.02 eV, with a wider absorption range extending to visible light region and could enhance their overall photocatalytic performance over the commercially TiO₂ nanoparticles. In Addition, it was demonstrated that the ratios of CNQDs to TiO₂ exhibited obvious influence on the photocatalytic performance of the obtained composite catalysts.By contrast to the pure TiO₂, all the CNQDs-x/TiO₂ composites displayed higher photocatalytic activities, and the CNQDs-2/TiO₂ possessed the highest photocatalytic degradation capacity towards bisphenol A with a reaction rate constant 0.30 (0.17 for pure TiO₂). Meanwhile, the H₂ production rate of CNQDs-2/TiO₂ sample is about 30 μmol g⁻¹ h⁻¹ higher than that of the pure TiO₂ nanoparticles. Moreover, the photocurrent intensity of CNQDs-2/TiO₂ was about 25 times higher compared to that of pure TiO₂ nanoparticles. Therefore, our research results can provide valuable guidance for exploring high-performance photocatalytic materials.