수열합성법으로 제작한 TiO2 나노로드의 특성과 이를 이용한 염료감응형 태양전지 제작 특성

김필중,박용섭 대한전자공학회 2023 전자공학회논문지 Vol.60 No.11

수열합성법을 이용하여 산화물 반도체인 TiO2 나노로드를 합성하였고, 화학첨가물인 염산(HCl)의 양을 6[ml]에서 10[ml]로 변화시키면서 TiO2 나노로드를 성장시켰다. 염료감응형 태양전지의 광전극으로 TiO2 나노로드를 사용하여 전지 특성을 평가하였다. 그 결과, 염산의 양을 증가시키면 성장된 TiO2 나노로드의 직경, 길이, 형태가 변화하는 것을 확인하였다. 6[ml]의 낮은 염산량에서 성장한 TiO2 나노로드는 막대 형태가 아닌 얇은 막 형태로 합성되었다. 염산의 양이 증가함에 따라 나노로드의 길이가 증가하여 직경의 변화에 기여하였으며, 염산의 양이 증가할수록 나노로드의 길이는 증가하고 나노로드의 직경은 감소하였다. 그러나 다량의 염산은 성장한 나노로드를 서로 뭉치는 경향이 있었다. 결과적으로 TiO2 나노로드의 직경과 길이를 변화시킬 때 염산의 양이 매우 중요한 변수임을 알 수 있었다. 이는 나노로드의 직경이 감소하고, 나노로드의 길이가 증가하며, 로드의 표면적이 넓어져 염료흡착량이 증가했기 때문이다. 이를 통해, 보다 효율적인 DSSC 구현이 가능해질 것으로 기대된다. The TiO2 nanorod as the oxide semiconductor was synthesized using hydrothermal synthesis method, and the TiO2 nanorod was grown while changing the amount of hydrochloric (HCl) acid from 6[ml] to 10[ml] as a chemical additive. Cell characteristics were evaluated using TiO2 nanorods as photo-electrodes of dye-sensitized solar cells. As a result, it was confirmed that increasing the amount of hydrochloric acid changed the diameter, length, and shape of the grown TiO2 nanorods. TiO2 nanorods grown in a low hydrochloric acid amount of 6[ml] were synthesized in a thin film form rather than a rod form. The length of the nanorods increased and contributed to the change in diameter as the amount of hydrochloric acid increased, Increasing the amount of hydrochloric acid increased the length of the nanorods and decreased the diameter of the nanorods. However, large amounts of hydrochloric acid tended to clump together the grown nanorods. As a result, it can be seen that the amount of hydrochloric acid is a very important variable when changing the diameter and length of TiO2 nanorods. This is because the diameter of the nanorods decreased, the length of the nanorods increased, and the surface area of the rods widened, increasing the amount of dye adsorption. This can be expected to enable more efficient DSSC implementation.

Enhanced H₂S sensing performance of TiO₂-decorated α-Fe₂O₃ nanorod sensors

Kheel, Hyejoon,Sun, Gun-Joo,Lee, Jae Kyung,Lee, Sangmin,Dwivedi, Ram Prakash,Lee, Chongmu Elsevier 2016 Ceramics international Vol.42 No.16

<P><B>Abstract</B></P> <P>Pristine and TiO<SUB>2</SUB> nanoparticle-decorated Fe<SUB>2</SUB>O<SUB>3</SUB> nanorods were synthesized via thermal oxidation of Fe thin foils, followed by the solvothermal treatment with titanium tetra isopropoxide (TTIP) and NaOH for TiO<SUB>2</SUB> nanoparticle-decoration. Subsequently, gas sensors were fabricated by connecting the nanorods with metal conductors. The structure and morphology of the pristine and TiO<SUB>2</SUB> nanoparticle-decorated Fe<SUB>2</SUB>O<SUB>3</SUB> nanorods were examined via X-ray diffraction and scanning electron microscopy, respectively. The gas sensing properties of the pristine and TiO<SUB>2</SUB> nanoparticle-decorated Fe<SUB>2</SUB>O<SUB>3</SUB> nanorod sensors with regard to H<SUB>2</SUB>S gas were examined. The TiO<SUB>2</SUB> nanoparticle-decorated Fe<SUB>2</SUB>O<SUB>3</SUB> nanorod sensor showed a stronger response to H<SUB>2</SUB>S than the pristine Fe<SUB>2</SUB>O<SUB>3</SUB> nanorod sensor. The responses of the pristine and TiO<SUB>2</SUB> nanoparticle-decorated Fe<SUB>2</SUB>O<SUB>3</SUB> nanorod sensors were 2.6 and 7.4, respectively, when tested with 200ppm of H<SUB>2</SUB>S at 300°C. The TiO<SUB>2</SUB> nanoparticle-decorated Fe<SUB>2</SUB>O<SUB>3</SUB> nanorod sensor also showed a faster response and recovery than the sensor made from pristine Fe<SUB>2</SUB>O<SUB>3</SUB> nanorods. Both sensors showed selectivity for H<SUB>2</SUB>S over NO<SUB>2</SUB>, SO<SUB>2</SUB>, NH<SUB>3</SUB>, and CO. The enhanced sensing performance of the TiO<SUB>2</SUB> nanoparticle-decorated Fe<SUB>2</SUB>O<SUB>3</SUB> nanorod sensor compared to that of the pristine Fe<SUB>2</SUB>O<SUB>3</SUB> nanorod sensor might be due to enhanced modulation of the conduction channel width, the decorated nanorods’ increased surface-to-volume ratios and the creation of preferential adsorption sites via TiO<SUB>2</SUB> nanoparticle decoration. The dominant sensing mechanism in the TiO<SUB>2</SUB> nanoparticle-decorated Fe<SUB>2</SUB>O<SUB>3</SUB> nanorod sensor is discussed in detail.</P>

Bond Strength of TiO2 Coatings onto FTO Glass for a Dye-sensitized Solar Cell

( Deuk Yong Lee ),( Jin Tae Kim ),( Young Hun Kim ),( In Kyu Lee ),( Myung Hyun Lee ),( Bae Yeon Kim ) 한국센서학회 2012 센서학회지 Vol.21 No.6

The bond strength of three types of TiO2 coatings onto fluorine-doped SnO2 (FTO) glass was investigated with the aid of a tape test according to ASTM D 3359-95. Transmittance was then measured using an UV-vis spectrophotometer in the wavelength range of 300 nm to 800 nm to evaluate the extent of adhesion of TiO2 nanorods/nanoparticles on FTO glass. A sharp interface between the coating layer and the substrate was observed for single TiO2 coating (TiO2 nanorods/FTO glass), which may be detrimental to the bonding strength. In multicoating sample (TiO2 nanorod/TiO2 nanoparticle/TiO2 nanoparticle/FTO glass), the tape test was not performed due to severe peeling-off prior to the test. On the other hand, the dual coating sample (TiO2 nanorod/TiO2 nanoparticle/FTO glass) showed minimum variation of transmittance (4%) after the test, suggesting that the topcoat adheres well with the FTO substrate due to the presence of the TiO2 nanoparticle buffer layer. The use of a TiO2 nanorod electrode layer with good adhesion may be attributed to the excellent dye sensitized solar cell performance.

Catalyst free rutile phase TiO2 nanorods as efficient hydrogen sensor with enhanced sensitivity and selectivity

Prakash Chandra,Dixit Ambesh 한국물리학회 2022 Current Applied Physics Vol.41 No.-

Using a low-cost hydrothermal method, we demonstrated the fabrication of phase pure rutile phase high-density vertically aligned TiO2 nanorods-based catalyst-free hydrogen (H2) gas sensor. The synthesized TiO2 nanorods on FTO are decorated with the aluminum interdigitated electrode pattern for electrical measurements. TiO2 nanorods-based hydrogen sensor showed the optimum response of ~53.18% at 150 ppm H2 concentration relative to air at 100 ◦C. The measured response and recovery time of TiO2 nanorods are 85 and 620 s, respectively. The TiO2 nanorods-based H2 gas sensor showed a relatively better response, good reproducibility, and stability at moderate temperatures, i.e., 50 and 100 ◦C. The electrochemical impedance measurements showed a small variation in the surface characteristics of TiO2 nanorods before and after exposing H2 gas. The carrier lifetime at 50 ◦C and 100 ◦C at 150 ppm are 5 μs and 3 μs, respectively. Interestingly, H2 selectivity is also observed against H2S, CO, and NH3 gases, suggesting that high-density vertically aligned TiO2 nanorods can be a good candidate for efficient hydrogen sensing at relatively low temperatures.

Effect of improved TiO2/FTO interface and surface modification via cocatalyst for a highly efficient and stable 3D Ni(OH)2/CdS/ZnIn2S4/TiO2 heterojunction

( Mahadik Mahadeo Abasaheb ),( Pravin S. Shinde ),이현휘,조민,장점석 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

A simple and effective strategy was used to fundamentally improve the performance of a heterostructuredNi(OH)2/CdS/ZnIn2S4/TiO2 photoanode. TiO2 nanorods grown hydrothermally on fluorine-doped tin oxide (FTO) were annealed at 500°C. The annealing effect minimized the defects in TiO2 grain boundaries and also aids to enhance the interface between the FTO and TiO2 nanorods for efficient electron transport. The stepwise introduction of ZnIn2S4 and CdS on annealed TiO2 improved both the absorption in the visible spectrum range and electron/hole separation in CdS/ZnIn2S4/TiO2. Additionally, the Ni(OH)2 co-catalyst can acts as effective hole trapping sites and improved the stability of the photoelectrode through the timely consumption of the photogenerated charges, particularly the holes.

Preparation and photocatalytic degradation of erbium doped titanium dioxide nanorods

Lee, Deuk Yong,Lee, Myung-Hyun,Cho, Nam-Ihn Elsevier 2012 Current Applied Physics Vol.12 No.4

<P><B>Abstract</B></P><P>Photocatalytic degradation of methylene blue (MB) in water was examined using Er<SUP>3+</SUP>-doped TiO<SUB>2</SUB> (Er–TiO<SUB>2</SUB>) nanorods prepared by a sol–gel derived electrospinning, calcination, and subsequent mechanical grinding. Different concentrations of Er dopant in the range of 0–1.0mol% were synthesized to evaluate the effect of Er content on the photocatalytic activity of TiO<SUB>2</SUB>. Among Er<SUP>3+</SUP>–TiO<SUB>2</SUB> catalysts, the 0.7mol% Er<SUP>3+</SUP>–TiO<SUB>2</SUB> catalyst showed the highest MB degradation rate. The degradation kinetic constant (<I>k</I>) increased from 1.0×10<SUP>−3</SUP>min<SUP>−1</SUP> to 5.1×10<SUP>−3</SUP>min<SUP>−1</SUP> with the increase of Er<SUP>3+</SUP> doping from 0 to 0.7mol%, but decreased down to 2.1×10<SUP>−3</SUP>min<SUP>−1</SUP> when Er<SUP>3+</SUP> content was 1.0mol%. It can be concluded that the degradation of MB under UV radiation was more efficient with Er<SUP>3+</SUP>–TiO<SUB>2</SUB> catalyst than with pure TiO<SUB>2</SUB>. The higher activity might be attributed to the transition of 4f electrons of Er<SUP>3+</SUP> and red shifts of the optical absorption edge of TiO<SUB>2</SUB> by erbium ion doping.</P> <P><B>Highlights</B></P><P>► Photocatalytic degradation of methylene blue was examined using Er<SUP>3+</SUP>–TiO<SUB>2</SUB> nanorods. ► Nanorods were prepared by electrospinning, calcinations and mechanical grinding. ► The 0.7mol% Er<SUP>3+</SUP>–TiO<SUB>2</SUB> catalyst showed the highest MB degradation rate. ► The degradation is attributed to the transition of 4f electrons of Er<SUP>3+</SUP>. ► And red shifts of the optical absorption edge of TiO<SUB>2</SUB> by erbium ion doping.</P>

Fabrication of A/R-TiO₂ composite for enhanced photoelectrochemical performance: Solar hydrogen generation and dye degradation

Mahadik, Mahadeo A.,An, Gil Woo,David, Selvaraj,Choi, Sun Hee,Cho, Min,Jang, Jum Suk Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.426 No.-

<P><B>Abstract</B></P> <P>Anatase/rutile TiO<SUB>2</SUB> nanorods composites were prepared by a facile hydrothermal method followed by dip coating method using titanium isopropoxide in acetic acid and ethanol solvent. The effects of the titanium isopropoxide precursor concentration, on the formation of dip coated anatase/rutile TiO<SUB>2</SUB> nanorods composite were systematically explored. The growth of anatase on rutile TiO<SUB>2</SUB> nanorods can be controlled by varying the titanium isopropoxide concentration. The morphological study reveals that anatase TiO<SUB>2</SUB> nanograins formed on the surface of rutile TiO<SUB>2</SUB> nanorod arrays through dip coating method. Photoelectrochemical analyses showed that the enhancement of the photocatalytic activities of the samples is affected by the anatase nanograins present on the rutile TiO<SUB>2</SUB> nanorods, which can induce the separation of electrons and holes. To interpret the photoelectrochemical behaviors, the prepared photoelectrodes were applied in photoelectrochemical solar hydrogen generation and orange II dye degradation. The optimized photocurrent density of 1.8mAcm<SUP>−2</SUP> and the 625μmolhydrogen generation was observed for 10mM anatase/rutile TiO<SUB>2</SUB> NRs composites. Additionally, 96% removal of the orange II dye was achieved within 5h during oxidative degradation under solar light irradiation. One of the benefits of high specific surface area and the efficient photogenerated charge transport in the anatase/rutile TiO<SUB>2</SUB> nanorod composite improves the photoelectrochemical hydrogen generation and orange dye degradation compared to the rutile TiO<SUB>2</SUB>. Thus, our strategy provides a promising, stable, and low cost alternative to existing photocatalysts and is expected to attract considerable attention for industrial applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dip coated A/R-TiO<SUB>2</SUB> composite strategy using titanium isopropoxide is proposed. </LI> <LI> Effective light scattering and improved charge transport improves the PEC performance. </LI> <LI> Composite enhances the photocurrent density of A/R-TiO<SUB>2</SUB> electrods. </LI> <LI> A/R-TiO<SUB>2</SUB> composite achieves hydrogen generation activity of 156.25μmol/h. </LI> <LI> A/R-TiO<SUB>2</SUB> composite exhibits excellent performance to remove orange (II) dye. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Surface analysis of N-doped TiO₂ nanorods and their enhanced photocatalytic oxidation activity

Hwang, Yun Jeong,Yang, Sena,Lee, Hangil Elsevier BV 2017 Applied Catalysis B Vol.204 No.-

<P><B>Abstract</B></P> <P>We investigated the presence of Ti<SUP>3+</SUP> defect sites on the surfaces of N-doped TiO<SUB>2</SUB> nanorods by using scanning transmission X-ray microscopy (STXM) and high-resolution photoemission spectroscopy (HRPES). The photo-oxidation activities of different types of N-doped TiO<SUB>2</SUB> nanorods were compared with each other and with their undoped nanorods. These nanorods were used to photocatalyze the oxidation of thiol molecules (i.e. 2-mercaptoethanol, benzenethiol, and 2-aminothiophenol) to disulfide and sulfonic (SO<SUB>3</SUB>H) species, and the conversion of CO to CO<SUB>2</SUB>, and their photocatalytic activities towards these reactions were assessed using HRPES and a residual gas analyzer, respectively. Conversion to further oxidized sulfonic species was only achieved on the N-doped TiO<SUB>2</SUB> surface compared to the non-doped TiO<SUB>2</SUB> nanorods. In addition, we found that longer N-doped TiO<SUB>2</SUB> nanorods (NTR-150) showed higher photo-oxidation activity than NTR-60, which resulted from their increased number of defect sites and narrowed band-gap.</P> <P><B>Highlights</B></P> <P> <UL> <LI> N-doped TiO<SUB>2</SUB> nanorod (NTR) has Ti<SUP>3+</SUP> and oxygen vacancy defect states on the surface. </LI> <LI> Longer NTR has higher photoactivity for thiol molecules oxidation and CO conversion. </LI> <LI> NTR can further oxidize −SH to sulfonic species unlike undoped TiO<SUB>2</SUB> nanorod. </LI> <LI> Greater number of defect states on NTR contribute to improved photocatalytic activity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced NO2 Gas-sensing Properties of SnO2 Nanorods with a TiO2 Capping

진창현,박성훈,김현수,고태경,이종무,정봉용 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.9

The influence of ZnO capping on the NO₂ gas-sensing properties of SnO₂ nanorods was examined. SnO₂-core/TiO₂-shell nanorods were fabricated by using a two-step process comprising the thermal evaporation of Sn powders and the metal-organic chemical-vapor deposition of TiO₂. The diameters of the SnO₂ nanorods ranged from a few tens to a few hundreds of nanometers, and the lengths were up to a few hundreds of micrometers. Transmission electron microscopy and X-ray diffraction showed that the cores and the shells of the nanorods were tetragonal-structured single crystal SnO₂ and amorphous TiO₂, respectively. Multiple networked SnO₂-core/TiO₂-shell nanorod sensors showed a response of 65.08% at NO2 concentration of 50 ppm at 100 ℃. The response of the SnO₂ nanorod sensors to 50-ppm NO₂ was increased 29 times when TiO₂ capping was used. This substantial improvement can be explained by using a space-charge model.

NH₂-MIL-125(Ti)/TiO₂ nanorod heterojunction photoanodes for efficient photoelectrochemical water splitting

Yoon, Ji Won,Kim, Do Hong,Kim, Jae-Hyeok,Jang, Ho Won,Lee, Jong-Heun Elsevier 2019 Applied catalysis. B, Environmental Vol.244 No.-

<P><B>Abstract</B></P> <P>A photoactive amine-functionalized Ti metal-organic framework (MOF) (MIL(125)-NH<SUB>2</SUB>(Ti)) layer is uniformly coated on vertically ordered TiO<SUB>2</SUB> nanorods (NRs) via a facile hydrothermal reaction, and the performance of the heterojunction photoanode in photoelectrochemical (PEC) water splitting is studied. The photocurrent density of the MIL(125)-NH<SUB>2</SUB>/TiO<SUB>2</SUB> NRs reaches 1.63 mA/cm<SUP>2</SUP> at 1.23 V vs. a reversible hydrogen electrode under AM 1.5 G simulated sunlight illumination, which is ∼2.7 times higher than that of pristine TiO<SUB>2</SUB> NRs. The incident photon-to-electron conversion efficiency of the MIL(125)-NH<SUB>2</SUB>/TiO<SUB>2</SUB> NRs improves significantly at λ<SUB>max</SUB> = 340 nm, implying the promotion of water oxidation through efficient light absorption and charge separation. The enhancement of the PEC activity in the TiO<SUB>2</SUB> NRs caused by an MIL(125)-NH<SUB>2</SUB> coating is discussed in relation to the surface area and elongated configuration of the TiO<SUB>2</SUB> NRs, the band gap of MIL(125)-NH<SUB>2</SUB>(Ti), and the type (II) heterojunction. This study demonstrates the rational design of heterojunctions between the semiconductor and the MOF, which paves the way for new facile and general approaches to achieve a high efficiency in water splitting.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Facile synthesis of NH<SUB>2</SUB>-MIL-125(Ti)/TiO<SUB>2</SUB> nanorod heterojunction photoanodes. </LI> <LI> Unprecedentedly high photocurrent density (1.63 mA/cm<SUP>2</SUP>) at 1.23 V vs. RHE. </LI> <LI> High photon-to-electron conversion efficiency (84.4%) at λ<SUB>max</SUB> = 340 nm. </LI> <LI> Efficient light absorption and charge separation promoted by type II interface. </LI> <LI> Excellent long-term stability of saturated photocurrent density for 1 month. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>