TiO2 QDs Research Articles

Ultrafast response humidity sensor based on titanium dioxide quantum dots/silica and its multifunctional applications

Humidity sensors with ultrafast response and recovery speed are very popular for humidity monitoring in dynamic environments such as complex operating conditions and human body monitoring. In this work, we prepared titanium dioxide quantum dots by hydrothermal synthesis and silica microspheres by Stober method. In addition, the electrostatic self-assembly method was used to prepare the two films with ultrafast response for moisture sensitivity. Due to the superhydrophilic properties of TiO2 QDs, water molecules can be adsorbed and resolved quickly on their surface. While the addition of SiO2 microspheres further increases the specific surface area of moisture-sensitive films and improves the moisture-sensitive properties of TiO2 QDs. The TiO2 QDs/SiO2 resistive humidity sensors not only exhibit excellent stability and repeatability, but also have fast water adsorption/desorption capacity. Between 11 % and 97 % relative humidity, the resistance change of the sensor reaches 6 orders of magnitude. In order to simulate the actual application environment, an experimental platform was built to verify the ultrafast response of the humidity sensor, and the response/recovery time of the sensor was as short as 22.4 ms/40.8 ms, which can quickly detect the change of humidity. The TiO2 QDs/SiO2 ultrafast humidity sensors proposed in this paper have great application potential in rapidly changing humidity environments such as complex working conditions, human body detection, humidity alarm and voice recognition.

Optical responsive asphalt coating with temperature-sensitive TiO2 quantum dots: Formula and temperature adaptability

The application of conventional asphalt contributes to extremely high pavement temperature in hot season as its black color entails large solar absorption. In this study, optical responsive asphalt is proposed to control pavement temperature, which is developed by introducing temperature-sensitive TiO2 quantum dots (TiO2 QDs) into traditional asphalt. Temperature-sensitive TiO2 QDs are prepared by blending thermochromic polymer and TiO2 quantum dots with varied concentrations. Optical characterizations on temperature-sensitive TiO2 QDs have demonstrated that peak value of solar absorption in temperature-sensitive TiO2 QDs at 45 °C is 14.29 %–22.86 % higher than that at 15 °C; the maximum fluorescent intensity of temperature-sensitive TiO2 QDs at 45 °C is 8.5 % higher than that at 15 °C. The results from optical characterizations on temperature-sensitive TiO2 QDs modified asphalt show that the incorporation of temperature-sensitive TiO2 quantum dots endows asphalt low solar reflectance at high temperature and high solar absorption at low temperature. Fluorescent intensity of modified asphalt at 45 °C is increased by 21.6 %, 10.2 % and 5.7 % than that at 15 °C for asphalt containing 5 %, 10 %, and 20 % temperature-sensitive TiO2 QDs, respectively. Indoor solar radiation simulation tests have revealed that compared with traditional asphalt, temperature-sensitive TiO2 QDs modified asphalt coating could yield cooling effectiveness of 6.4 °C at high temperature. Meanwhile, outdoor solar radiation test indicates TiO2 QDs modified asphalt coating could realize warming effectiveness of 0.7 °C at low temperature. The outcomes on temperature-sensitive TiO2 QDs modified asphalt with temperature-adaptability properties makes an advancement in functional pavement.

Incorporation of Cu5FeS4 QDs with Abundant Oxygen Vacancy TiO2 QDs/TiO2 OVs: Double S-Scheme Photocatalysts for Effectual N2 Conversion to NH3 under Simulated Solar Light.

Photocatalytic N2 conversion to NH3 is a green, sustainable pathway with renewable energy sources and carbon neutrality. In this research, ternary TiO2 QDs/TiO2 OVs/Cu5FeS4 nanocomposites were prepared by an easy and affordable procedure and utilized to produce clean ammonia energy without a sacrificial agent. The amount of produced green ammonia by the optimum nanocomposite achieved was 17,274 μmol L-1 g-1, which was approximately 20.9, 6.48, 4.45, 2.26, and 1.45 times higher than those of commercial TiO2, TiO2 QDs, TiO2 OVs, Cu5FeS4, and TiO2 QDs/TiO2 OVs photocatalysts, respectively. Lattice compatibility through the developed homojunction within TiO2 QDs/TiO2 OVs and the integration of Cu5FeS4 nanoparticles led to the establishment of a double S-scheme homo/heterojunction system, which improved the photocatalytic activity by maintaining electrons and holes with high oxidation and reduction power and greatly reduced the recombination of charges, which led to the acceleration of charge transfer and migration. Besides, the promoted surface area compared to the pure components, introducing oxygen vacancies, and reducing the particle size boosted the photocatalytic N2 conversion to NH3. The results of this research are a basis for the rational design of homojunction/heterojunction visible-light-responsive systems for photocatalytic nitrogen fixation reactions.

Synthesis and characterization of TiO2-graphene heterostructured quantum dots by electrochemical process

Titanium dioxide (TiO2) is a trendily attractive semiconductor owing to its optical and electrical properties within the UV-visible range. Nevertheless, limitations such as instability in the UV range and rapid recombination of photogenerated charge carriers leading to poor efficiency in photoactivity are major limiting factors that hold back the application of the materials on large scale. In order to tackle the stated issues, graphene quantum dots (GQDs), with their high carrier conductivity, UV-stability and thermal conductivity, can be used to improve TiO2’s flaws as optoelectronic materials. As a suitable edge transporter and modifier, GQDs can be grown as heterostructure well-bonded with TiO2 quantum dots. This material modification can lead to combined benefits of using TiO2 QDs’ preferable optoelectronic properties in UV-visible range and GQDs’ high conductivity and stability. This allows the synthesis of heterostructured quantum dots that can be tailored towards wide range of applications such as electron transport layer materials in perovskite solar cells or highly stable colloidal-based photocatalysts. In this study, TiO2/GQDs nanocomposites were synthesized using a solution-based electrochemical process with citric acid and potassium chloride (KCl) acting as electrolytes. Our proposed recipe yielded heterostructured QDs with average size of 3.44 nm well below the exciton Bohr radius of both TiO2 and graphene and hydrodynamic sizes around 45-59 nm with zeta potential in range of -24 to 30 mV. This yielded colloidal solution with stability and surface ion tunability based on KCl concentration with 0.3 M being the most stable recipe. Additionally, absorption band edge can also be tuned within the range of 2.8-3.9 eV which can be adjusted with concentration of KCl based on the desired applications.

Integration of TiO2 QDs with brown TiO2: S-scheme photocatalysts with boosted activity for simulated sunlight-driven N2 fixation without hole quencher

An alternative strategy to solve the energy consumption and pollution problems caused by traditional ammonia production is photocatalytic N2 fixation. Therefore, the rational design and facile synthesis of photocatalysts for the efficacious ammonia production is an active research hotspot. In this research, TiO2 QDs (TQDs) and brown TiO2 (BTO) nanoparticles were combined through a facile hydrothermal method. The optimal homojunction TQDs/BTO (1:1) photocatalyst with QDs size of about 4.5 nm was utilized for ammonia production, for the first time, with the activity of 11844 µmol L−1 g−1, which was almost 14.5, 4.46, and 3.07-folds as large as TiO2 (P25), TQDs, and BTO materials, respectively. In addition, the presence of hydrazine intermediate in the ammonium formation pathway and the impact of hydrogen-free solvents, electron quencher, and acidic and basic solutions on ammonia production were investigated. The electrochemical and spectroscopic characterizations confirmed that the boosted ability of photocatalyst is related to the boosted adsorption of N2 molecules and effective segregation/transfer of charge carriers. Consequently, the S-scheme TQDs/BTO (1:1) homojunction photocatalyst could be a suitable photocatalyst in N2 fixation technology, with high stability for repeated use and a facile synthesis route.

Recycling and photodegradation processes of organic hazardous materials on polyaniline-titanium dioxide quantum dots catalyst

A photo-catalyst with conducting polymers doped with titanium dioxide, known as TiO2 quantum dots (TiO2 QDs), has a high efficiency for photocatalytic usage. The organic hue methyl orange was broken down in the current study using polyaniline (PANI) and polyaniline titanium dioxide quantum dots (PANI-TiO2 QDs) polymers. PANI and PANI-TiO2 QDs have been produced by chemical oxidative polymerization in an aqueous solution. By characterization of PANI-TiO2 QDs nanocomposites using ultraviolet–visible (UV–vis), Fourier transform infrared (FTIR), and X-ray powder diffraction (XRD), it was demonstrated that the chemical structure of polymer composites had not changed after being doped with TiO2 QDs. To determine the form, size, surface area, and thermal analyses of the produced PANI-TiO2 QDs samples, EDX, BET, and TGA were used. The photocatalytic activity of the PANI-TiO2 QDs in the photo-degradation of methyl orange dye as an organic hazardous chemical in an aqueous medium was assessed using a 50-watt xenon lamp light source and direct sunlight. PANI-TiO2 QDs demonstrated high photocatalytic properties, with a 93% efficiency, as opposed to 35% and 60.1%, respectively, for PANI and TiO2 QDs. When PANI, titanium dioxide quantum dots, and PANI-TiO2 QDs are present during the recycling processes in the presence of all created samples up to four times, the photo-degradation rate decreases by about 50.2%, 15.4%, and 17.4%, respectively.

Highly adsorbent Ca2+/La3+ doped TiO2 quantum dots for tetracycline degradation under visible light

In this study, titanium dioxide quantum dots (TiO2 QDs) were synthesized and doped with 0–5 mol% Ca2+ and La3+ via hydrolysis of titanium tetraisopropoxide and hydrothermal microwave treatment at 120 °C for 10 min. As a result, the Ca2+/La3+ doped TiO2 QDs presented a crystallite size of ∼5 nm, estimated by the Scherrer equation. The samples with 1 mol% Ca2+ showed a high BET surface area (412.19 m2 g−1) and an increase of the interfacial component (64%) led to a highly energetic and adsorptive QDs surface. XRD and Raman analyses showed anatase as the main crystal phase. A red shift in the Raman spectrum induced a rise in the oxygen vacancies formation. The band gap of the QDs was calculated by the Tauc Plout method, which reached values of 2.72 eV, in the case of doping with 1 mol% of Ca+2. Finally, the degradation of 96% tetracycline in 30 min of photocatalysis using the Ca2+/La3+ doped TiO2 QDs was reached under visible light.

TiO2 QDs/MoSe2 heterojunctions for enhanced photo-excited charge separation and gas sensing performance

2D transition metal selenides are facing challenges in the field of gas sensing due to their short carrier lifetime and low utilization rate. Along these lines, in this work, MoSe2 nanosheets were successfully synthesized by solvothermal method, and modified with TiO2 QDs. P-N heterostructures with the advantage of quantum dot constraint effect are constructed. The developed heterojunction can effectively promote the separation and transfer of the generated charges, under the excitation of ultraviolet light, while the room temperature sensitivity of the material for the detection of NO2 is enhanced.

Anatase quantum dots decorated silica/carbon lamellas for removal of antipsychotic drugs via adsorption-photocatalysis and toxicity evaluation.

In this work, discrete quantum dots of crystallized anatase TiO2 are successfully anchored on carbon nanosheets containing amorphous SiO2 via templated self-assembly and pyrolysis routes. The novel hybrid photocatalyst of TiO2/C/SiO2 exhibits well coupled adsorption and visible light photocatalysis on chlorpromazine (CPZ) and the rate constants are 0.0223 and 0.0198 min-1, respectively. The direct photocatalytic degradation of CPZ under static conditions reaches 91.1% within 3h while a removal rate of 31.4% for CPZ could be retained under dynamic flow conditions, and the improved performance could be attributed to enhanced adsorption via SiO2/C and highly exposure of TiO2 QDs surface. Based on the trapping experiments, ESR, LC-MS, and toxicity evaluation, O2- free radicals are identified as main reactive species for CPZ degradation along three possible pathways, with reduced toxicities for its intermediates. The cell viability tests of photocatalytic-degraded solutions and the catalyst exhibit negligible toxicities for both intermediates and the material, suggesting the novel composite of TiO2/C/SiO2 as an environmental friendly photocatalyst for pharmaceutical wastewater treatment.

Titanate quantum dots-sensitized Cu2S nanocomposites for superficial H2 production via photocatalytic water splitting

TiO2 quantum dots-sensitized Cu2S (Cu2S/TiO2) nanocomposites with varying concentration of TiO2 QDs are synthesized via a facile two-stage hydrothermal-wet impregnation method. X-ray diffraction analysis confirms the formation of Cu2S and TiO2with chalcocite and anatase phases, respectively. The observed shoulder-like absorption peaks indicate the UV–visible light-driven properties of the composite. Morphological analysis reveals that the fabricated Cu2S/TiO2 composite consists of Cu2S with a nano rod-like shape (average length and width of ∼856 and ∼213 nm, respectively) and nanosheets-like structures (average length and width of ∼283 and ∼289 nm, respectively), whereas the TiO2 is formed as quantum dots with a size range of 8.2 ± 0.4 nm. Chemical state analysis shows the presence of Cu+, S2−, Ni2+, and O2− in the nanocomposite. The H2 evolution rate over the optimized photocatalyst is found to be ∼45.6 mmol h−1g−1cat under simulated solar irradiation, which is around 5 and 2.4-fold higher than that of the pristine TiO2 and Cu2S, respectively. Continuous H2 production for 30 h is achieved during time-on-stream experiments, demonstrating the excellent stability and durability of the Cu2S/TiO2 photocatalyst for large-scale applications.

Room-temperature gas sensors based on titanium dioxide quantum dots for highly sensitive and selective H2S detection

Room-temperature gas sensors with high performance are crucial in practical application. This work prepared a series of controllable-size titanium dioxide quantum dots (TiO2 QDs) via a rapid microwave-assisted solvothermal method for detecting ppb-level H2S at room temperature. The effect of reaction temperature on the nanostructure and gas sensing properties was investigated systematically. The characterization results showed the samples presented ultra-small size (around 5–6 nm) nanostructure and modified surface state (including Ti3+ and oxygen defects). The S120-TiO2 QDs gas sensor showed the best sensing properties towards ppb-level H2S at room temperature, including high response (25.12 @ 500 ppb H2S), rapid response/recovery, low detecting limit level, good selectivity, and operating stability. The gas sensing mechanism was explained through the synergetic effect of ultra-small size nanostructure, large specific surface area, and surface defects, which are in favor of improving the surface activity and charge transfer efficiency. Moreover, the practical application of TiO2 QDs gas sensor in detecting the volatiles of fish (Pangasius) was also verified. This work developed a room temperature TiO2 quantum dots-based gas sensor, which is promised for practical application because of the rapid synthesis and high performance.

N‐doped TiO2‐quantum dots tightly anchored on graphene with superior interfacial contact via C–Ti bond

AbstractA novel composite of N‐doped TiO2‐quantum dots tightly anchored on graphene (denoted as N‐doped TiO2‐QDs@GP) with superior interfacial contact via C–Ti bond was synthesized via the simple one‐pot vapor‐thermal method. The as‐obtained N‐doped TiO2‐QDs@GP includes TiO2 QDs with an average size of 3.28 nm uniformly distributed on the surface of GP. The large specific area and superior interfacial contact via C–Ti bond ensured its potential photocatalytic application. Except for the effective interfacial charge transfer achieved via C–Ti chemical bond between TiO2 QDs and GP, its enhanced visible light absorption and larger oxygen vacancy ratio also make contributions. Electron spin resonance spectra (ESR) were used to study the photocatalytic mechanism, which proved the participation of both superoxide radical (·O2−) and hydroxyl radical (·OH) in the photocatalytic reactions. This work provides a promising one‐pot method for constructing intimately contacted N‐doped TiO2/GP composite with superior interfacial contact via C–Ti bond and excellent photocatalytic activities.

Construction of heterojuncted photocatalyst with TiO2 quantum dots and graphene oxide nanosheets for highly efficient photocatalysis

To overcome the recombination issue of photocarriers, TiO2 quantum dots (QDs, nanoparticles in a few nanometers) were used to form heterojunctions with graphene oxide nanosheets. This combination has significantly enhanced the photocatalytic activity by providing more active reaction sites at the nanoscale surface and suppressing photocarrier recombination through fast separating the photocarriers by the internal electric field in the TO2/graphene oxide heterojunctions. The enhancement in photocatalytic activity has been evidenced by the improved hydrogen generation rate in photoelectrochemical water splitting, which is about 30% higher than that of bare TiO2 QDs in the same situation. Moreover, the TiO2/graphene oxide composite exhibits a lower flat band potential, which means a higher reducing potential of photo-excited electrons.

BiOBr and BiOCl decorated on TiO2 QDs: Impressively increased photocatalytic performance for the degradation of pollutants under visible light

BiOBr and BiOCl were decorated on TiO2 QDs through n-p-p heterojunctions by a simple strategy and they were applied for degradation of three organic dyes upon visible illumination. The obtained photocatalysts were analyzed via XRD, FESEM, EDX, UV–vis DRS, PL, BET, TEM, HRTEM, FT-IR, EIS, XPS, and transient photocurrent measurements. The TiO2 QDs/BiOBr/BiOCl nanocomposite with 20% wt. of BiOBr and 30% wt. of BiOCl displayed superior photoability in the degradation of methylene blue, rhodamine B, and fuchsine, which was almost 34.5, 176, and 78.7-times larger than TiO2 and 27.8, 13.5, and 51.5-folds greater than TiO2 QDs, respectively. The results show that the construction of intimate n-p-p heterojunctions between BiOBr, TiO2 QDs, and BiOCl counterparts leads to enhanced visible-light harvesting and improved charge separation, resulted efficiently increased photocatalytic activity. The trapping results proved that h+, •O2−, and OH• species have considerable effects on the degradation reaction. We think that the improved efficiency of the ternary TiO2 QDS/BiOBr/BiOCl photocatalyst is a splendid alternative for the removal of toxic contaminants from wastewater.

A BICHROMOPHORIC ORGANIC-INORGANIC SEMICONDUCTOR NANOCOMPOSITE: DEVICE READY BROAD SPECTRAL RESPONSE LIGHT-HARVESTING MATERIAL WITH ENHANCED PHOTORESPONSE

Herein, an improved light harvesting organic–inorganic nanocomposite material was obtained by coupling a judiciously developed green-orange absorbing bichromophoric organic salt [R6 G][HFl] and UV-blue absorbing TiO2 QDs. The designed bichromophoric salt is synthesized using a biphasic metathesis reaction and the nanocomposite [R6 G][HFl]-TiO2 is then obtained by single phase overnight stirring of the two components in an optimized ratio. The synthesized nanocomposite results in further broadening of absorption spectrum ranging from UV to NIR with the peak approximately matching the solar irradiation spectrum and demonstrate enhanced absorptivity thereby capable of harvesting the major part of the solar emission. The nanocomposite demonstrates a perfect molecular as well as HOMO-LUMO and valence band–conduction band alignment which enables energy transfer from TiO2 to [R6 G][HFl] and charge transfer between duo as evident from steady state and transient photoluminescence studies. White light irradiation of the nanocomposite film exhibits 450 times higher photocurrent than that of the bare TiO2 film. The slow photocurrent decay time of 46 s confirms that a generous amount of photo generated carriers harvest in the composite sample. This unique nanocomposite structure demonstrating spectral broadening along with charge transfer result in extraordinarily improved photocurrent and photoresponse thereby rendering [R6 G][HFl]-TiO2 nanocomposite an excellent potential active material for a solid state TiO2 based Heterojunction Solar Cell (HJSC). Efficiency of this nanocomposite based HJSC was found to be the highest (4.4 %) among the various other layer by layer structured devices thereby presenting a simplified cell fabrication technique by excluding the necessity of usual layer by layer dye deposition on TiO2 followed by their optimization for best efficiency. Thus, this study presents a thoughtfully designed device ready perfect active material for a TiO2 based HJSC exhibiting good competence.

Construction of Heterojuncted Photocatalyst with TiO <sub>2</sub> Quantum Dots and Graphene Oxide Nanosheets for High-Efficient Photocatalysis

To overcome the recombination issue of photocarriers, TiO2 quantum dots (QDs, nanoparticles in a few nanometers) were used to form heterojunctions with graphene oxide nanosheets. This combination has significantly enhanced the photocatalytic activity by providing more active reaction sites at the nanoscale surface and suppressing photocarrier recombination through fast separating the photocarriers by the internal electric field in the TiO2/graphene oxide heterojunctions. The enhancement in photocatalytic activity has been evidenced by the improved hydrogen generation rate in photoelectrochemical water splitting, about 30% higher than that of bare TiO2 QDs in the same situation. Moreover, the TiO2/graphene oxide composite also exhibits a lower flat band potential, which means a higher reducing potential of photo-excited electrons.

A Z-scheme TiO2 quantum dots fragment-Bi12TiO20 composites for enhancing photocatalytic activity

To completely utilize the high redox ability of photo-induced charge carriers. Here, a Z-scheme photocatalyst of TiO2 QDs/Bi12TiO20 (TBT) composites with TiO2 QDs fragment attached to the surface of Bi12TiO20 (BTO) was prepared and the photocatalytic activity was evaluated by degradation of gatifloxacin (GF). The optimal photocatalytic performance of TBT displayed 3 times higher than bare BTO. The improved photocatalytic performance was ascribed to the effective separation of the charge carriers between TiO2 QDs and BTO via the direct Z-scheme heterojunction. Such a strategy for the construction of Z-scheme TBT composites for removal of organic pollutants, proving new insights into design photocatalyst.

TiO2 quantum dots loaded sulfonated graphene aerogel for effective adsorption-photocatalysis of PFOA

With the pollution of perfluoroalkyl substances (PFASs) became increasingly serious, the researches focused on removal of PFASs by adsorption-photocatalysis method has attracted considerable attention. To make the catalyst TiO2 disperse uniformly as quantum dots onto hydrophobic surface which was liable to attract perfluorooctanoic acid (PFOA), the surfactant sodium dodecyl sulfate (SDS) were used in this work, which not only connected the hydrophilic TiCl3 to the hydrophobic sulfonated graphene (SG) nanosheets, but also behaved as the molecular template for controlled nucleation and growth of the nanostructured TiO2. After 3D SG-TiO2 QD nanosheets were fabricated, a series of 3D SG-TiO2 QD aerogels were self-assembled by ice-template. TiO2 uniformly distributed on the surface of SG aerogel at QD size level (2–3 nm) and the size of TiO2 could be effectively regulated by concentration of SDS. Compared with aggregated TiO2 material, 3D SG-TiO2 QD aerogels owned higher adsorption and photocatalytic performance. Benefiting from the hydrophobic surface of 3D SG as well as dispersed TiO2 QDs, 3D SG-TiO2 QD could enrich PFOA instantaneously (0.0381/s) and photocatalytic decomposed them effectively (1.898 E−4/s). PFOA degradation by hole and hydroxyl radicals proceeded via a stepwise mechanism. The column made of 3D SG-TiO2 QD could remove PFOA persistently in cycles of permeation. 3D SG-TiO2 QD possessed powerful adsorption-photocatalytic decomposition capability of PFOA and steady reusability performance. The present work highlights the individual roles and synergistic effect of TiO2 QD and 3D SG for effectively removing PFOA.

Preparation of novel ternary TiO2 QDs/CDs/AgI nanocomposites with superior visible-light induced photocatalytic activity

In this research, visible-light-induced TiO2 QDs/CDs/AgI photocatalysts were synthesized by simple refluxing strategy. Various instruments such as TEM, HRTEM, FESEM, EDX, XRD, XPS, PL, EIS, photocurrent, FT-IR, BET, UV–vis DRS, and Mott–Sckottky were exploited to investigate their characteristics. Photocatalytic abilities of the as-obtained samples were assessed by decomposition of MB, fuchsine, RhB, and phenol upon visible light. The optimum TiO2 QDs/CDs/AgI (30%) nanocomposite completely degraded RhB after 30 min. This enhancement is about 77, 6, and 2.7 times as premiere as those of the bare TiO2, TiO2 QDs, and TiO2 QDs/CDs (0.25 mL) samples, respectively. These increments of photocatalytic ability is credited to the more generation and transfer of e–/h+ pairs among TiO2 QDs, CDs, and AgI counterparts and improved textural features. The higher photocatalytic activity and long-term stability results proved that the TiO2 QDs/CDs/AgI (30%) nanocomposite could be an auspicious candidate for the elimination of different organic contaminants in the ecosystem. Moreover, a reasonable mechanism for the photodegradation of pollutants was also proposed.

CdS/TiO2 heterojunction in glass matrix: Synthesis, characterization, and application as an improved photocatalyst

In this paper, sodium borosilicate glass SiO2-B2O3-Na2O-ZnO with 2 wt% CdS and 1 wt% TiO2 were prepared by the melt quench technique. For the growth of QDs, single-step heat treatment was given using glass transition (Tg) and glass crystallization (Tc) temperature. Hexagonal and anatase phase of grown CdS and TiO2 QDs were confirmed by XRD pattern. The size of powders was observed by SEM and cluster formation of CdS/TiO2 QDs was studied by FESEM. EDS pattern confirms the elemental composition which was used during synthesis. The structural changes due to heat treatment were explored by FTIR study. The growth of QDs and size determination was done by HRTEM. An increase in the size of QDs with annealing time was confirmed by optical absorption and emission spectra.Photocatalytic activity of Cd3:3 h (5.33 μm) and Cd3:5 h (3 μm) is investigated by degrading indigo carmine (IC) dye and degradation efficiency was found to be 85.30% and 91.64% respectively for 5 h.