P25 TiO2 Research Articles

Highly-accessible, doped TiO2 nanoparticles embedded at the surface of SiO2 as photocatalysts for the degradation of pollutants under visible and UV radiation

A series of photocatalysts consisting of C- and N-doped titanium dioxide (TiO2) nanoparticles highly dispersed and firmly embedded at the surface of a silica matrix were prepared using a novel synthesis method in which activated carbon has a double role: it acts as support for depositing the TiO2 nanoparticles and as hard template for generating a silica matrix that embeds them. Additionally, the use of activated carbon in combination with ammonia during the synthesis led to carbon and nitrogen doping of the TiO2 domains, which enhanced their absorption of radiation in the visible range. The combination of these features led to higher activity (i.e. higher removal % and TON) in the photocatalytic degradation of probe pollutants (phenol and rhodamine B) compared to the benchmark P25 TiO2 under UV and, even more markedly, under visible radiation. Particularly, the photocatalyst prepared with 10 wt% of TiO2 nanoparticles (10%TiO2NP@SiO2) displayed much enhanced TON values under visible radiation compared to P25 TiO2 (a 12 times higher TON with rhodamine B, and an 8 times higher TON with phenol). The TON values are also significantly higher compared to any previously reported TiO2-SiO2 photocatalyst. The TiO2NP@SiO2 photocatalysts can be effectively reused in consecutive runs. The photocatalytic activity of the prepared materials was correlated to their physicochemical properties by means of a thorough characterisation using a combination of techniques (XRD, ICP-OES, N2 physisorption, TEM, UV–vis, FT-IR and XPS).

Modeling the photocatalytic oxidation of carboxylic acids on aqueous TiO2 suspensions and on immobilized TiO2-chitosan thin films in different reactor geometries irradiated by UVA or UVC light sources

Photocatalytic reactor models incorporating radiation transport parameters and intrinsic kinetic parameters of photocatalytic decomposition of single-compound and mixtures of oxalic (OA) and formic acid (FA), in both slurry suspensions and immobilized photocatalytic thin films, were validated in two well-mixed annular photoreactors geometries irradiated with either UVA or UVC radiation. The six-flux absorption scattering model (SFM) predicted the radiation field in a titanium dioxide (TiO2 P25) catalyst suspension, the local volumetric rate of photon absorption (LVRPA) at each point of the reactor and, after volumetric integration, the lumped VRPA. The model combining the lumped VRPA, the kinetics models describing the adsorption and photocatalytic decomposition of OA and FA and the material balance of the reacting species was fitted to the experimental results of photocatalytic decomposition of OA and FO in a slurry TiO2 suspension, to determine the OA and FA intrinsic reaction kinetics parameters. Such intrinsic parameters were then used with the average surface rate of photon absorption (SRPA) to model and predict the photocatalytic oxidation of OA and FA on non-porous TiO2–chitosan films immobilized on glass plates immersed in the photoreactor. The models for both slurry suspensions and immobilized photocatalysts predicted the degradation and mineralization of OA and FA and of a mixture of them under diverse experimental conditions. This study demonstrates a systematic methodology for determining intrinsic reaction kinetics rate parameters of water contaminants that can also be used to represent the photocatalytic oxidation of such contaminants in irradiated slurries and in immobilized photocatalytic thin films and in any photoreactor geometry.

Temperature-Induced Variations in Photocatalyst Properties and Photocatalytic Hydrogen Evolution: Differences in UV, Visible, and Infrared Radiation

In this work, solar-heating-induced temperature-based photocatalytic hydrogen evolution reaction (PC-HER) of different photocatalysts (TiO2 P25, g-C3N4, and their loaded Pt) was comprehensively stu...

Do Gas Nanobubbles Enhance Aqueous Photocatalysis? Experiment and Analysis of Mechanism

The performance of photocatalytic advanced oxidation must be improved in order for the technology to make the jump from academic research to widespread use. Research is needed on the factors that cause photocatalysis to become self-limiting. In this study, we introduced, for the first time, nanobubbles continuously into a running photocatalytic reactor. Synthetic air, O2, and N2 bubbles in the size range of 40 to 700 nm were added to a reaction system comprising P25 TiO2 photocatalyst in stirred aqueous solution excited by UV-A lamps, with methyl orange as a target contaminant. The removal of methyl orange was tested under conditions of changing pH and with the addition of different radical scavengers. Results indicated that the oxygen and air nanobubbles improved the photocatalytic degradation of methyl orange—the removal efficiency of methyl orange increased from 58.2 ± 3.5% (N2 aeration) to 71.9 ± 0.6% (O2 aeration). Dissolved oxygen (DO) of 14.93 ± 0.13 mg/L was achieved using O2 nanobubbles in comparison to 8.43 ± 0.34 mg/L without aeration. The photodegradation of methyl orange decreased from 70.8 ± 0.4% to 53.9 ± 0.5% as pH increased from 2 to 10. Experiments using the scavengers showed that O2− was the main reactive species in photocatalytic degradation under highly dissolved oxygen conditions, which also accounted for the observation that the removal efficiency for methyl orange decreased at higher pH. However, without photocatalyst, nanobubbles alone did not improve the removal of methyl orange, and nanobubbles also did not increase the degradation of methyl orange by only photolysis. These experiments show that oxygen and air nanobubbles can act as environmentally friendly catalysts for boosting the performance of photocatalytic water treatment systems.

Photocatalytic dyes degradation on suspended and cement paste immobilized TiO2/g-C3N4 under simulated solar light

To overcome the shortcomings of fast recombination of photo-induced carriers and powder recycling difficulty of graphitic carbon nitride (g-C3N4), a powder suspension system containing TiO2/g-C3N4 and a cement paste immobilization of TiO2/g-C3N4 were fabricated through pyrolysis of urea and P25 TiO2, and spraying method, respectively. The phase composition, microstructure, element chemical state, optical properties, and photocatalytic degradation of dyes were investigated. TiO2 particles were attached closely to the surfaces of g-C3N4. TiO2/g-C3N4 had broader light absorption ranges and a lower recombination rate of photo-induced carriers. During the photocatalysis, h+, •O2- and •OH were the main active species. The heterojunction structure of TiO2/g-C3N4 belonged to a Z-scheme heterojunction. The TiO2/g-C3N4 powders had ~97% degradation efficiency of rhodamine B (RhB) dyes after 40 min irradiation. After five cycles of degradation, the degradation efficiency reduced to ~67%. The TiO2/g-C3N4 cement paste had superior degradation over RhB and methylene blue (MB). After five cycles of degradation, the photocatalytic cement paste still had higher efficiency, ~98% after 60 min degradation. A photocatalytic mechanism was proposed. TiO2/g-C3N4 powders and TiO2/g-C3N4 cement pastes can be one of highly promising photocatalysts for large-scale water treatment.

Hollow N-TiO2/MnO2 nanocomposite based yeast biomass for gaseous formaldehyde degradation under visible light

Synthesis of new hollow nano-composite photocatalysts based yeast biomass has been considered as a future innovation technology to control air pollution. This work demonstrates that a green, environmentally friendly, sustainable, and facile hydrothermal carbonization route of low-cost and renewable yeast biomass used to fabricate natural doping N-colloidal carbon spheres (NCSs) as a hard template for hollow N-TiO2/MnO2. The presence of natural doping nitrogen serves as a stabilizer and reductant. Hence, the yeast provided a solid frame with deposits nitrogen to form the hybrid N/yeast precursor. The resulting NCSs were obtained by hydrothermal method at 180°C for 6h. The characterization was performed using SEM, TEM, XRD, FTIR and N2 adsorption/desorption analysis. It was found that the findings fully retained the morphology of the yeast cells and the size of the hollow spheres was about 1.5–2μm. The results of catalytic test showed that the new hollow nanosphere N-TiO2/MnO2 possessed a higher photodegradation activity for gaseous formaldehyde under visible irradiation than the commercial TiO2, due to their higher surface area (160m2g−1), hollow structure and superior reducibility. Its catalytic efficiency was attained to be more than 90%, which is about 10 times higher than that of the conventional catalyst TiO2–P25.

Solar-driven valorization of glycerol towards production of chemicals and hydrogen

Reverse microemulsion-based synthesis was successfully applied to the preparation of nanosized TiO2 particles in anatase and rutile crystalline phases. The resulted nano-oxides were found to have smaller average crystalline size, higher surface area and narrower band gap than commercial TiO2 samples, P25 and DT-51. All the TiO2 materials were used as supports for platinum nanoparticles prepared by incipient wetness impregnation and deposition-precipitation methods. The photo-catalytic activities of these materials were compared in the reaction of glycerol photo-reforming in aqueous media using simulated solar light. The results showed that different crystalline phases of titania have different effects on hydrogen production and selectivity of intermediate products. Anatase was found to be more selective towards glyceraldehyde, while the presence of rutile promoted a more selective reaction towards glycolaldehyde. Rutile also exhibited a higher productivity of hydrogen compared to anatase.

Efficiency enhancement in dye-sensitized solar cells with co-sensitized, triple layered photoanode by enhanced light scattering and spectral responses

A method for impressive efficiency enhancement in TiO2-based nanoparticle (NP) dye-sensitized solar cells (DSSCs) is demonstrated by using a co-sensitized triple layered photoanode, comprising a nanofibre (NF) layer of TiO2 sandwiched between two TiO2 P25 NP layers. Rose Bengal (RB) and Eosin-Y (EY) dyes are used for the co-sensitization. DSSCs with conventional TiO2 (P25) NP bi-layer photoanode (NP/NP), sensitized with EY, showed an overall power conversion efficiency (η) of 0.89% under the illumination of 100 mW cm–2 (AM 1.5) with iodide-based liquid electrolyte. Whereas DSSCs fabricated with triple layered photoanode (NP/NF/NP) with the same total thickness and sensitized with EY yielded 1.77% efficiency under the same illumination conditions, showing an impressive ~99% enhancement in the overall power conversion efficiency. The DSSCs fabricated with RB-sensitized NP/NP and NP/NF/NP photoanodes showed 0.25 and 0.73% efficiencies, respectively. Upon optimization, DSSCs fabricated with co-sensitized NP/NP bi-layer and NP/NF/NP triple layer photoanodes showed 1.04 and 2.09% efficiencies, respectively, showing again an impressive ~100% enhancement in η due to the co-sensitized triple layer photoanode structure. Increase in the short circuit photocurrent density, UV–visible absorptions measurements, incident photon to current efficiency and electrochemical impedance spectroscopic measurements confirmed that this enhancement is very likely due to the enhanced light harvesting and reduction of recombination of photoelectrons combined with the enhanced spectral responses of the co-sensitized triple layered photoanode.

Ketoprofen degradation by surface reactive species on TiO2, AgxOy/MoxOy/catalysts

In this research, the surface functionalization of TiO2 by silver and molybdenum species was used for the degradation and mineralization of ketoprofen. The catalyst was synthesized by a controlled wet impregnation method and characterized by several techniques; mineralization and degradation were quantified with HPLC and TOC (Total Organic Carbon) achieving more than 40 and 60% according to the pH. The higher removal using bimetallic synthesized catalyst compared with P25 TiO2 is due to the surface species, Ag, Ag+, MoO3, and Mo5+ that decrease the bandgap energy that inhibit the recombination of photoelectrons and charge separation. The as-synthetized nanocomposites stand as an alternative for the non-steroidal-anti-inflammatory drug commonly found in wastewater.

Photocatalytic conversion of sodium lignosulfonate into vanillin using mesoporous TiO2 derived from MIL-125

Mesoporous TiO2 with regular pancake-like morphology was synthesized by facile calcination of MIL-125 (MIL = Materials of Institut Lavoisier) at different temperatures. The optimal sample MT400 (calcination at 400 °C) is composed of nanoparticles with a size of about 10 nm and mesopores of about 4–12 nm. Its specific surface area can reach up to 174 m2 g−1. In the photocatalytic conversion of sodium lignosulfonate, the yield of vanillin over MT400 is 2.1 mg/g, obviously superior to that over P25 TiO2 (0.27 mg/g). MT400 with a large specific surface area offers sufficient active sites, and its mesoporous structure provides pathways for the transport of charge carriers and products, giving a satisfactory photocatalytic performance for vanillin generation. It is proved that h+ and ·O2− play the key role for vanillin generation from sodium lignosulfonate. This work indicates that MOF-derived metal oxides hold great promise in the application of biomass (photo)catalytic valorization.

Solid-state synthesis and photodegradation property of anatase TiO2 micro-nanopowder by sodium replacement

To investigate the effect of the doping of alkali metal on the band structure and photocatalytic property of titanium oxide crystals, the mesoporous sodium doped titanium dioxide (Na–TiO2) micro-nano powder was synthesized by the solid-state reaction (SSR) method, and characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectrum (UV–Vis), scanning electron microscopy/energy dispersive spectroscopy, X-ray photoelectron spectroscopy (XPS), N2 desorption-adsorption. Meanwhile, the UV-degradation properties of Na–TiO2 and P25–TiO2 powder materials for hydroquinone (HQ) were studied. The results show that sodium ions with the low charge density entered into the (004) crystal place of anatase TiO2, producing the dislocation defects of TiO2 crystal structure. The spherical-like morphology micro-nanopowder with a size of 50–500 nm, sodium content of 3.36(wt%), the bandgap width of 3.08 eV, BET surface area of 111.52 m2/g, the pore size distribution center of 4.72 nm, the pore volume of 0.32 cm3/g are obtained, respectively. Within 60min and 25 °C, the UV-degradation rate (97.32%) of mesoporous Na–TiO2 powders for hydroquinone is 2.62 times for that (37.08%) of P25–TiO2 powder. It is mainly derived from the increase of dislocation density of Na–TiO2 powder, and the results of the synergistic photocatalystic degradation of hydroxyl radicals and superoxide radicals. And the photocatalytic efficiency is associated with pH value, photocatalyst dosage, concentration of HQ, irradiation time and stability.

Graphitic carbon nitride embedded with graphene materials towards photocatalysis of bisphenol A: The role of graphene and mediation of superoxide and singlet oxygen

Composite photocatalysts comprising graphitic carbon nitride (g-C3N4) and graphene materials were synthesized and evaluated in the photocatalysis of bisphenol A (BPA) with a focus on elucidating the reaction mechanism. Embedding reduced graphene oxide (rGO) to g-C3N4 significantly accelerated the photocatalysis rate of BPA by three folds under visible light irradiation at neutral pH. We showed that rGO synthesized in intimate contact with g-C3N4 increased the surface areas and electrical conductivity of the g-C3N4 composites and promoted the electron-hole pair separation. The BPA photodegradation mechanism involved selective oxidants as superoxide (O2•−) and singlet oxygen (1O2) that were formed through one-electron reduction of O2 and the unique oxidation of O2•− by photogenerated hole (h+), respectively. The synthesized photocatalyst exhibited superior visible light photoreactivity to that of N-doped P25 TiO2, good photo-stability and reuse potential, and was operative in complex wastewater. rGO embedded g-C3N4 achieved good photomineralization of BPA at 80% in 4 h compared to 40% of bare g-C3N4. This study sheds light on the photocatalysis mechanism of BPA with a metal-free, promising rGO/g-C3N4 photocatalyst.

Visible-Light Photocatalyst to Remove Indoor Ozone under Ambient Condition

Ozone is a kind of hazardous gas in indoor areas and needs to be removed in order to protect the human respiratory system. Previous methods include physical adsorption, thermal treatment, electromagnetic radiation removal, catalysis and photocatalysis. However, they all have limited effects. This research introduced a novel milestone to remove indoor ozone by utilizing visible light photocatalysis technique under ambient condition. The modified sol–gel method was applied to prepare photocatalysts, strontium titanate (SrTiO3) and rhodium-doped strontium titanate (SrTiO3:Rh). In addition, the SrTiO3:Rh was further immersed in N3 dye to improve its photocatalytic performance. Batch system and continuous-flow system were used to quantify the removal rate of ozone and to measure the conversions of ozone, respectively. The results showed that SrTiO3:Rh possessed a higher ozone removal rate under a visible light condition compared with a commercial P25 TiO2 catalyst. In addition, SrTiO3:Rh based catalysts can also successfully perform visible light ozone photodecomposition in the continuous ozone flow system. Note that current ozone converters in aircraft utilize thermal-catalysts, which can only be operated at high temperature. This research reveals a promising catalysts and photo process, which can possibly replace the current aircraft ozone converters with visible-light driven converters, and boast higher performance under ambient condition.

Surface modification of blue TiO2 with silane coupling agent for NOx abatement

The role of hydroxyl-functionalization of reduced TiO2 (Blue TiO2) for the photocatalytic oxidation of toxic NOx was systematically explored in the present study. A hydrogenation technique was used to reduce the rutile phase in P25 TiO2 giving rise to a Magneli phase. Then, the process was followed by the surface functionalization of the Blue TiO2 with Trimethoxy (Propyl) Silane (TPS). The fabricated nanoparticles were structurally characterized, and photocatalytically tested for NOx abatement. OH-functionalized Blue TiO2 showed strong photo-oxidation of NOx with NOx removal efficiency of 80.2%. The broad-band light absorption (UV and visible) and the formation of a higher number of radicals on the surface of OH-functionalized Blue TiO2 made the material more efficient than other samples. In addition, the lowest NO2 selectivity of 2.7% proved the effective suppression of toxic NO2 and formation of nitrate ions. The reusability test was carried out for five cycles of 1 ​h and had 10% loss in NOx removal efficiency. The role of surface OH groups for the oxidation of NO and NO2 has been discussed in this manuscript. A possible mechanism for NOx photo-oxidation is proposed based on FTIR, ESR, and ion chromatography test.

Physicochemical properties and photocatalytic de-NOx performance of TiO2 nanostructures via microwave hydrothermal strategy

TiO2 nanostructures have been prepared via microwave hydrothermal process using different NaOH concentrations. The physicochemical properties of the products were systematically investigated by using UV–vis Diffuse Reflectance Spectra, X-ray Photoelectron Spectra, Photoluminescence Spectra, Raman, N2 adsorption-desorption, and Transmission Electron Microscope analysis. The results indicated a close correlation between the NaOH concentration and different types of nanostructured titania products obtained from the microwave-assisted hydrothermal process. At low NaOH concentrations (4 M and 6 M), the precursor TiO2 nanoparticles partially converted into a mixture of one dimensional (1D) nanostructures (e.g., nanorods or nanowires) and 2D nanostructures such as nanosheets. As the NaOH concentration is increased to 8 M and 10 M, the obtained TiO2 products contain nanosheet and nanotube-like structures, respectively, with a significantly larger specific surface area. The photocatalytic performance of the synthesized TiO2 products, prepared under different NaOH concentrations, were evaluated through the toxic NOx gas removal efficiencies. The nanostructured TiO2 samples prepared at a higher NaOH concentration have shown improved de-NOx efficiencies than the TiO2–P25 precursor.

Effect of amination of titanium dioxide in the TiO2/rGO composite on the efficient photocatalytic removal of gaseous formaldehyde at room temperature

Abstract In order to obtain the advanced photocatalyst with high performance for removing the gaseous formaldehyde, a new strategy with amination of titanium dioxide (TiO2) and combination with reduced graphene oxide (rGO) is proposed in this work. TiO2 was first aminated into amino-TiO2 and then combined with rGO by an electrostatic self-assembly process to form the amino-TiO2/rGO photocatalysts. The structure and morphology were characterized by XRD, FTIR, and SEM, respectively. Physicochemical properties were measured by EIS, XPS, ESR, PL, and photocurrent measurements. The mechanism of the photocatalytic reaction was studied. Optimal amino-TiO2/rGO catalyst exhibits high catalytic activity and recyclability. The reaction rate constant of HCHO over this catalyst is approximately 9.8 × 10−3 L mol−1 ·min−1, which is 10.5 times higher than that of the commercial Degussa P25 TiO2. The analysis results from XPS and ESR indicates that the high catalytic activity could be mainly attributed to the imine formed by chemisorption of amino and HCHO. The reaction speed of formaldehyde photolysis increases as the concentration of HCHO on the photocatalyst surface increased. In addition, the introduction of graphene enhances carrier separation efficiency so that leads to more reactive radicals such as hydroxyl radicals (·OH) and superoxide radicals (·O2−), leading to improved performance on formaldehyde photolysis. This could provide a useful method for highly efficient formaldehyde photocatalysis.

Photocatalytic NOx removal using tantalum oxide nanoparticles: A benign pathway

A wet chemical-synthesized high surface area ultrafine Ta2O5 nanoparticle and its application to NOx control is reported. The as-synthesized photocatalyst is characterized using powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), transient absorption spectroscopy (TAS), UV–vis diffuse reflectance spectroscopy, and N2 adsorption (BET). The catalytic performance of these Ta2O5 nanoparticles was evaluated towards the photodegradation of nitrogen oxides (NOx) under UV–vis irradiation at room temperature. In comparison to the commercial TiO2 (Aeroxide P25 powder: 20 % rutile/80 % anatase, 50 m2/g), traditionally considered state-of-the-art material for the NOx degradation, as-synthesized Ta2O5 (41 m2/g specific surface area) nanoparticles offers NOx remediation with minimal toxic NO2 and excellent stability under UV irradiation. A 2-fold increase in the UV-photonic-efficiency (∼0.64 %) of Ta2O5 is observed compared to TiO2 P25 (∼0.30 %). NO conversion using Ta2O5 was noted to be 18.6 % compared to 8.8 % for TiO2. The UV–vis photocatalytic activity is explained on the basis of the band structure modulation of Ta2O5 due to the intrinsic defects introduced during the synthesis of the material.

Z-scheme indium sulfide/bismuth oxybromide heterojunctions with enhanced visible-light photodegradation of organics

Heterojunction photocatalysts with intimate contact are very promising for organics photodegradation due to their high efficiency in enhancing the light absorption, inhibiting the carrier recombination and improving the photogenerated electron/hole separation. In this study, we demonstrated a two-step hydrothermal method to construct indium sulfide/bismuth oxybromide (In2S3/BiOBr) heterojunctions for the first time. Importantly, the optoelectronic dynamics of carrier separation efficiency, charge transport and electron/hole recombination rate were tuned to an optimal domain through a series of experiments. As a result, the photocatalytic activity of In2S3/BiOBr heterojunctions was greatly enhanced under visible-light irradiation. The as-synthesized IS/BOB-0.2 heterojunctions exhibited the highest photocatalytic ability, which was approximately 4.75 times and 11.26 times higher than that of pure BiOBr and TiO2 P25 catalysts. This work will provide a better insight into the formation mechanism BiOBr-based Z-scheme heterojunctions with high photocatalytic performance.

Water oxidation by P25 TiO2 photoanodes in acidic solution

P25 TiO2 photoanodes are used to photo-oxidise water in two different acids, 0.5 M H2SO4 and 1 M HClO4. In the former acid, the linear sweep voltammogram, LSV, appears to exhibit two photocurrent waves, whilst only one in the latter. In 0.5 M H2SO4, the recorded LSV coupled with a low faradaic efficiency (0.58) for the photooxidation of water to O2, fO2, and a significant level of persulfate, fS2O8 = 0.12, shows that the electrochemical kinetics are not simply those for water oxidation. In 1 M HClO4, the LSV coupled with a high fO2 value (0.91) suggest that the photocurrent is due to water oxidation. Photo-induced absorption spectroscopy, PIAS, measurements made using the P25 TiO2 photoanode reveal a steady state absorbance change, ΔAbsss, associated with the steady-state concentration of surface accumulated holes, [h+]ss, which varies with: (i) monitoring wavelength, with a peak at ca. 500 nm, and (ii) applied potential, flattening off at ca. 0.7 V vs Ag/AgCl. PIAS measurements, coupled with concomitant transient photocurrent (TC) measurements, on the P25 TiO2 photoanode polarised at 1.3 v vs Ag/AgCl, in 1 M HClO4, show that the oxidation of water is second order with respect the concentration of the surface-accumulated, photogenerated holes, [h+]ss, which have a calculated turnover frequency of 19 s−1, under 1 sun irradiation. This is the first reported example of the use of PIAS/TC to probe the photoelectrochemical kinetics exhibited by a mesoporous semiconductor photoanode derived from a powder, for water oxidation and the significance of such is discussed briefly.

Toxicity assessment of synthesized titanium dioxide nanoparticles in fresh water algae Chlorella pyrenoidosa and a zebrafish liver cell line

This study aims to assess the toxicity of the commonly-spread titanium dioxide nanoparticles (TiO2 NPs) by evaluating the exposure impact of the particles on both freshwater algae Chlorella pyrenoidosa and zebrafish liver cell line (ZFL), the two common in vitro models in toxicological studies. To compare the toxic effects of TiO2 NPs with different physiochemical properties, three types of manufactured TiO2 were used: bulk TiO2, Degussa P25 TiO2, and ultrafine TiO2 NPs. Both short and long-term biological responses of green algae, such as the effect on the cell growth rate, pigment autofluorescence, and esterase activity were investigated. The dosage, physical property of TiO2 particles, and their interactions with algal cells affect cellular growth, especially after short-term exposure. The hydrodynamic size plays a critical role in determining the acute toxicity to C. pyrenoidosa in terms of autofluorescence and esterase activity, while all types of TiO2 NPs show toxic effects after exposure for 14 days. However, this observation is not seen when studying the effect of introduced particles in ZFL, for the precipitated Degussa P25 TiO2 showed the highest cellular inhibition. Interestingly, despite the obvious overall toxicity toward C. pyrenoidosa, the photocatalytical properties of TiO2 NPs may contribute to the enhanced photosynthesis in the low concentration range (<40 µg mL−1). Overall, we found that the physical interactions between TiO2 particles and the cells, particles’ size and dispersibility play critical role in the cytotoxic effect for both algal and ZFL cells, while the photocatalytical properties of TiO2 particles may produce mixed effects on the cytotoxicity of green algae.