급격한 과학기술의 발전으로 미세먼지 배출량이 증가함에 따라 대기오염은 심각한 환경·사회 문제로 꾸준히 대두되고 있고, 이에 따 라 미세먼지 증가로 인한 질병 및 이상기후 증가로 인한 도로이동원에서의 교통사고 발생률 등의 문제점이 증가할 수 있다. 이를 해 결하기 위해 미세먼지 저감을 목적으로 건설분야에서 널리 사용되고 있는 광촉매 물질인 TiO2를 콘크리트의 광촉매 반응을 증가시키 고 광원의 효율적 이용을 위한 방안으로 투수콘크리트에 적용한 TiO2를 혼입한 투수콘크리트 포장 기술개발 기초 연구를 진행하였다. 실험결과, TiO2\혼입에 따른 투수콘크리트의 압축강도의 변화는 영향을 미치지 않는 미미한 수준으로 나타났다. TiO2를 혼입한 투수 콘크리트를 도로이동원에 적용하기 위해서는 동결융해 저항성 등 내구특성 및 미세먼지 저감 성능 등의 추가적인 실험이 필요할 것으 로 판단된다.

Nanoparticles are commonly used to avoid the opaque white color of TiO2 based sunscreen. However, a dispersing agent is typically required because of the tendency of the nanoparticles (NPs) to agglomerate. Stearic acid is one kind of dispersing agent often used for sunscreen products. However, according to the MSDS data sheet on stearic acid, stearic acid is highly hazardous to aquatic life and causes irritation on human skin. To avoid this problem, in this study a safer organic dispersing agent extracted from Korean seaweed has been studied to disperse TiO2 nanoparticles, and further use as an active agent in sunscreen products. The presence of phytochemicals in seaweed extract, especially alginate, can disperse TiO2 nanoparticles and improve TiO2 dispersion properties. Results show that seaweed extract can improve the dispersion properties of TiO2 nanoparticles and sunscreen products. Reducing the agglomeration of TiO2 nanoparticles improves sunscreen properties, by making it less opaque white in color, and increasing UV protection value. It was also confirmed that adding seaweed extract into sunscreen products had no irritating effects on the human skin, making it more desirable for cosmetics application.

Semiconductor-based photocatalytic carbon dioxide ( CO2) reduction is of great scientific importance in the field of alleviating global warming and energy crisis. Surface amine modification and cocatalyst loading on the catalyst surface could improve CO2 adsorption capacity and photogenerated charge separation. Herein, amine-modified brookite–TiO2 ( NH2–B–TiO2) coupled metal species (Cu, Ag, Ni(OH)2) cocatalysts have been successfully synthesized by chemical reduction method. The photocatalytic CO2 reduction results show that the CH4 production rates of NH2– B–TiO2/Cu, NH2– B–TiO2/Ag, and NH2– B–TiO2/Ni(OH)2 are 3.2, 12.5, and 1.7 times that of NH2– B–TiO2 (0.74 μmmol g− 1 h− 1), respectively. Results show the introduction of metal species on the surface of the catalyst enhances the absorption range of sunlight and the photogenerated carrier separation efficiency, resulting in enhancing the performance of photocatalytic CO2 reduction. This work provides a strategy for designing metal species-loaded amine-modified brookite–TiO2 by surface/interface regulation to improve photocatalytic efficiency.

PURPOSES : The increase in particulate matter due to increased air pollutant emissions has become a significant social issue. According to the Ministry of Environment, air pollutants emitted from large-scale businesses in 2022 increased by 12.2% compared to the previous year, indicating that air pollution is accelerating owing to excessive industrialization. In this study, TiO2, which is used to reduce airborne particulate, was used. The TiO2 coating fixation and dynamic pressure coating-type TiO2 fixation methods were used to solve the material peeling phenomenon caused by gravity, which is a limitation when the TiO2 penetration method is applied to a vertical concrete structure along the road. The long-term durability and performance were analyzed through environmental resistance and NOx removal efficiency evaluation experiments. These analyses were then assessed by comparing the NOx removal efficiency with the dynamic pressure permeationtype TiO2 fixation method used in previous studies. METHODS : To evaluate the long-term durability and performance of the TiO2 coating fixation method and dynamic pressure coating TiO2 fixation method for vertical concrete structures, specimens were manufactured based on roadside vertical concrete structures. Environmental resistance tests such as the surface peeling resistance test (ASTM C 672) and freeze-thaw resistance test (KS F 2456) were conducted to evaluate the long-term durability. To evaluate the long-term performance, the NOx removal efficiency of TiO2 concrete owing to road surface deterioration during the environmental resistance test was evaluated using the NOx removal efficiency evaluation equipment based on the ISO 22197-1 standard. This evaluation was compared and analyzed using the dynamic pressure infiltration TiO2 fixation method. RESULTS : The long-term durability of the TiO2 coating fixation and dynamic pressure coating TiO2 fixation methods were evaluated using environmental resistance tests. During the surface peeling resistance test, the TiO2 material degraded and partially detached from the concrete. However, the NOx removal efficiency was ensured by the non-deteriorated and fixed TiO2 material. The long-term performance was confirmed through a freeze-thaw resistance test to evaluate the NOx removal efficiency after 300 cycles of surface deterioration. The results showed that when the TiO2 coating fixation and dynamic pressure infiltration TiO2 fixation methods were applied to vertical concrete structures, the durability of the structure was not compromised. In comparison to the dynamic pressure infiltration TiO2 fixation method, the NOx removal efficiency observed during the surface peeling resistance test was lower, while the freeze-thaw test exhibited notably higher removal efficiency. CONCLUSIONS : To solve the material peeling phenomenon caused by gravity, the long-term durability and performance were evaluated by applying the TiO2 coating fixation and dynamic pressurized coating TiO2 fixation methods to vertical concrete specimens. Long-term durability was confirmed through environmental resistance tests, and long-term utility was secured by measuring the NOx removal efficiency according to surface degradation. These findings show that implementing the TiO2 coating fixation method and dynamic pressure coating TiO2 fixation methods on-site effectively reduce NOx.

Photocatalytic CO2 reduction is a promising approach for reducing CO2 emissions and achieving the goal of carbon neutrality. In this work, selectively coupling Cu(OH)2 and CuO with amine-modified brookite TiO2 ( NH2–B–TiO2) has been achieved by a simple precipitation method. The results show that CuO is better than Cu(OH)2 as a co-catalyst to enhance the CO2 photoreduction capability of NH2– B–TiO2. The highest rates of CO2 conversion to CH4 and CO of NH2– B–TiO2–CuO composite reach 6.05 and 3.25 μmol h− 1 g− 1, respectively, which is higher than 8 times the yield of CH4 of NH2– B–TiO2. It is proposed that the NH2– B–TiO2–CuO composite offers an effective charge transfer through the formation of a p–n junction between NH2– B–TiO2 and CuO interfaces, while in the NH2– B–TiO2–Cu(OH)2 composite, the Cu(OH)2 dominantly serves as an electron sink to capture photo-induced electrons, promoting photo-induced carrier separation. This work provides an ingenious synthetic method for selectively anchoring Cu(OH)2 and CuO on semiconductors with different charge transfer routes for an efficient CO2 photoreduction.

Decabromodiphenyl ether (BDE209) is a persistent aromatic compound widely associated with environmental pollutants. Given its persistence and possible bioaccumulation, exploring a feasible technique to eradicate BDE209 efficiently is critical for today’s environmentally sustainable societies. Herein, an advanced nanocomposite is elaborately constructed, in which a large number of titanium dioxide ( TiO2) nanoparticles are anchored uniformly on two-dimensional graphene oxide (GO) nanosheets ( TiO2/GO) via a modified Hummer’s method and subsequent solvothermal treatment to achieve efficient photocatalytic degradation BDE209. The obtained TiO2/ GO photocatalyst has excellent photocatalytic due to the intense coupling between conductive GO nanosheets and TiO2 nanoparticles. Under the optimal photocatalytic degradation test conditions, the degradation efficiency of BDE209 is more than 90%. In addition, this study also provides an efficient route for designing highly active catalytic materials.

PURPOSES : The purpose of this study was to evaluate the performance of a titanium dioxide (TiO2) asphalt surface treatment agent for reducing NOx on the roadside at laboratory and full scales. METHODS : To verify the NOx reduction performance of TiO2 and silicon-based resin-applied surface treatment agents at the lab scale, a bed flow photo reactor test (ISO standard) and a mixed tank photo reactor test designed to apply real-scale construction materials were conducted. Subsequently, the full-scale NOx reduction performance was verified using a full-scale demonstration facility, and the field construction capability of the TiO2 asphalt surface treatment agent was verified through actual road site application. RESULTS : The bed flow photoreactor and mixed tank photoreactor methods showed the same trend in the NOx removal performance. Evaluation of the NOx removal performance of the TiO2 surface treatment agent revealed that the NO removal rate was approximately 13% at the laboratory scale and 15% at full scale. CONCLUSIONS : Through this study, it was determined that the asphalt surface treatment agent applied with TiO2 will have a sufficient NOx reduction effect in an actual road site. In the future, it will be necessary to analyze the continuity of the effect according to traffic volume through continuous monitoring in the field.

PURPOSES : Advancements in science and technology caused by industrialization have led to an increase in particulate matter emissions and, consequently, severity of air pollution. Nitrogen oxide (NOx), which accounts for 58% of road transport pollutants, adversely affects both human health and the environment. A test-bed was constructed to determine NOx removal efficiency at the roadside. TiO2, a material used to reduce particulate matter, was used to remove NOx. It was applied to a vertical concrete structure using the dynamic pressurized penetration TiO2 fixation method, which can be easily applied to vertical concrete structures. This study was conducted to evaluate the NOx removal efficiency of the dynamic pressurized-penetration TiO2 fixation method in a test-bed under real roadside conditions. METHODS : A test-bed was constructed in order to determine the NOx removal efficiency using the dynamic pressurized penetration TiO2 fixation method on the roadside. The dynamic pressurized-penetration TiO2 fixation method was applied by installing a vertical concrete structure. NOx was injected into the test-bed using an exhaust gas generator. By installing a shading screen, the photocatalytic reaction of TiO2 was suppressed to a maximum concentration of 1000 ppb along the roadside. The removal efficiency was evaluated by measuring NOx concentrations. In addition, illuminance was measured using an illuminance meter. RESULTS : From the results of the analysis of the NOx removal efficiency in the test-bed which the dynamic pressurized type TiO2 fixation method was applied to, an average removal efficiency ranging from 18% to 40% was achieved, depending on the illuminance. Similarly, according to the results of the evaluation of the NO removal efficiency, an average of removal efficiency ranging from 20% to 62% was achieved. Thus, the NOx removal efficiency increased when the illuminance was high. CONCLUSIONS : From the results of the experiment conducted, the efficiency of NOx removal per unit volume was obtained according to the illuminance of TiO2 concrete along an actual road. Field applicability of the dynamic pressurized-penetration-type TiO2 fixation method to vertical concrete structures along roads was confirmed.

The conversion of CO2 into solar fuels by photocatalysis is a promising way to deal with the energy crisis and the greenhouse effect. The introduction of oxygen vacancy into semiconductor has been proved to be an effective strategy for enhancing CO2 photoreduction performance. Herein, TiO2- x nanostructures have been prepared by a simple solvothermal method and engineered by the reaction time. With the prolonging of reaction time, the oxygen vacancy signal gradually increases while the band gap becomes narrow for the as-synthesized TiO2- x nanostructures. The results show that the TiO2- x-6 h, TiO2- x-24 h, and TiO2- x-48 h samples have the main product of CH4 (more) and CO (less) for CO2 photoreduction. Among the three oxygen vacancy photocatalysts, the TiO2- x-24 h sample shows the highest CH4 generation rate of 41.8 μmol g− 1 h− 1. On the basis of photo/electrochemical measurements, the TiO2- x-24 h sample exhibits efficient electron–hole separation and charge transfer capabilities, thus allows much more electrons to participate in the reaction and finally promotes the photocatalytic CO2 reduction reaction. It further confirms that the optimization of oxygen vacancy concentration could facilitate the photoinduced charge separation and accordingly improve photocatalytic CO2 conversion.

N-doped Na2Ti6O13@TiO2 (denoted as N-NTO@TiO2) composites are successfully synthesized using a simple two-step process: 1) ball-milling of TiO2 with Na2CO3 followed by heat treatment at 900oC; 2) mixing of the prepared Na2Ti6O13 with titanium isopropoxide and calcining with urea at 500oC. The prepared composites are characterized using XRD, SEM, TEM, FTIR, and BET. The N-NTO@TiO2 composites exhibit well-defined crystalline and anatase TiO2 with exposed {101} facets on the external surface. Moreover, dopant N atoms are uniformly distributed over a relatively large area in the lattice of the composites. Under visible light irradiation, ~51% of the aqueous methylene blue is photodegraded by N-NTO@TiO2 composites, which is higher than the values shown by other samples because of the coupling effects of the hybridization of NTO and TiO2, N-doping, and presence of anatase TiO2 with exposed {101} facets.

For the selective catalytic reduction of NOx with ammonia (NH3-SCR), a V2O5WO3/TiO2 (VW/nTi) catalyst was prepared using V2O5 and WO3 on a nanodispersed TiO2 (nTi) support by simple impregnation process. The nTi support was dispersed for 0~3 hrs under controlled bead-milling in ethanol. The average particle size (D50) of nTi was reduced from 582 nm to 93 nm depending on the milling time. The NOx activity of these catalysts with maximum temperature shift was influenced by the dispersion of the TiO2. For the V0.5W2/nTi-0h catalyst, prepared with 582 nm nTi-0h before milling, the decomposition temperature with over 94 % NOx conversion had a narrow temperature window, within the range of 365-391 °C. Similarly, the V0.5W2/nTi-2h catalyst, prepared with 107 nm nTi-2h bead-milled for 2hrs, showed a broad temperature window in the range of 358~450 °C. However, the V0.5W2/Ti catalyst (D50 = 2.4 μm, aqueous, without milling) was observed at 325-385 °C. Our results could pave the way for the production of effective NOx decomposition catalysts with a higher temperature range. This approach is also better at facilitating the dispersion on the support material. NH3-TPD, H2-TPR, FT-IR, and XPS were used to investigate the role of nTi in the DeNOx catalyst.

Interest in the use of semiconductor-based photocatalyst materials for the degradation of organic pollutants in a liquid phase has grown, due to their excellent performance and response to the light source. Herein, we fabricated a NiO-SiCTiO2 ternary structured photocatalyst which had reduced bandgap energy, with strong activation under UV-light irradiation. The synthesized samples were examined using XRD, SEM, EDX, TEM, DRS, EIS techniques and photocurrent measurement. The results confirmed that the two types of metal oxides were well bonded to the SiC fiber surface. The junction of the new photocatalyst exhibited a large number of photoexcited electrons and holes. The holes tended to oxidize the water and form a hydroxyl radical, which promoted the decomposition of methylene blue. The close contact between the 2D SiC fiber and metal oxide semiconductors expanded the scope of absorption wavelength, and enhanced the usability of the ternary photocatalyst for the degradation of methylene blue. Among three synthesized samples, the NiO-SiC-TiO2 showed the best photocatalytic effect, and was considered to have excellent photoelectron transfer due to the synergy effect between the metal oxide and SiC.

A spin coating process for RRAM, which is a TiN/TiO2/FTO structure based on a PTC sol solution, was developed in this laboratory, a method which enables low-temperature and eco-friendly manufacturing. The RRAM corresponds to an OxRAM that operates through the formation and extinction of conductive filaments. Heat treatment was selected as a method of controlling oxygen vacancy (VO), a major factor of the conductive filament. It was carried out at 100 oC under moisture removal conditions and at 300 oC and 500 oC for excellent phase stability. XRD analysis confirmed the anatase phase in the thin film increased as the heat treatment increased, and the Ti3+ and OH- groups were observed to decrease in the XPS analysis. In the I-V analysis, the device at 100 oC showed a low primary SET voltage of 5.1 V and a high ON/OFF ratio of 104. The double-logarithmic plot of the I-V curve confirmed the device at 100 oC required a low operating voltage. As a result, the 100 oC heat treatment conditions were suitable for the low voltage driving and high ON/OFF ratio of TiN/TiO2/FTO RRAM devices and these results suggest that the operating voltage and ON/OFF ratio required for OxRAM devices used in various fields under specific heat treatment conditions can be compromised.

This study compares the characteristics of a compact TiO2 (c-TiO2) powdery film, which is used as the electron transport layer (ETL) of perovskite solar cells, based on the manufacturing method. Additionally, its efficiency is measured by applying it to a carbon electrode solar cell. Spin-coating and spray methods are compared, and spraybased c-TiO2 exhibits superior optical properties. Furthermore, surface analysis by scanning electron microscopy (SEM) and atomic force microscopy (AFM) exhibits the excellent surface properties of spray-based TiO2. The photoelectric conversion efficiency (PCE) is 14.31% when applied to planar perovskite solar cells based on metal electrodes. Finally, carbon nanotube (CNT) film electrode-based solar cells exhibits a 76% PCE compared with that of metal electrodebased solar cells, providing the possibility of commercialization.