TiO2 Nanorod Arrays Research Articles

TiO2 nanorod arrays modified by NiFe-layered double hydroxide nanosheets for boosting photoelectrochemical water splitting

TiO2 nanorod arrays modified by NiFe-layered double hydroxide nanosheets for boosting photoelectrochemical water splitting

Self-powered Sb2S3 photodetectors with efficient carrier transport enabled by compact vertical TiO2 nanorods.

Antimony sulfide (Sb2S3) photodetectors (PDs) possess extensive application prospects. Efficient carrier transport of a PD significantly affects the detectivity and response speed. Herein, we propose an all-inorganic self-powered Sb2S3 PD based on vertical TiO2 nanorods (NRs). The spray-coated 15-nm TiO2 thin film as a seed layer ensures the growth of compact vertical TiO2 nanorod arrays by the hydrothermal method. One-dimensional TiO2 nanorods facilitate photocarrier separation and transport to enhance device performance. Ultimately, the Sb2S3 PD achieves a responsivity of 0.29 A/W, a specific detectivity of 3.37 × 1012 Jones, and a response time of 7.8 µs, showing great potential in commercial applications.

Electroless Ag nanoparticle deposition on TiO2 nanorod arrays, enhancing photocatalytic and antibacterial properties

Hypothesis: The use of a high surface area, hence small nanoparticles for photocatalysis, makes them difficult to remove from solution. Producing photocatalysts on substrates would alleviate this limitation. Adding heterojunctions to photocatalysts, for example, TiO2/Ag, could improve photocatalytic performance due to Schottky junction formation and introduce antibacterial properties.Experiments: TiO2 nanorod arrays were synthesised on a substrate via a hydrothermal approach, on which Ag nanoparticles were deposited using an electroless plating technique with varied deposition times and metal precursor concentrations. Photocatalytic performance was evaluated by monitoring Rhodamine B (RhB) degradation under ultraviolet light and antibacterial properties of the films tested using Methicillin-resistant Staphylococcus aureus.Findings: The Ag nanoparticle content was controlled by the Ag deposition process. The TiO2/Ag nanorod array containing 6.6 atomic% Ag as nanoparticles of ∼ 25 nm in diameter degraded 88 % of the RhB in 6 h compared to 54 % degradation for bare TiO2 nanorods under the same reaction conditions. Decreased photoluminescence with heterojunction formation would indicate electron transfer from the TiO2 into the Ag nanoparticles, thereby reducing charge carrier recombination. The antibacterial test conducted in the dark revealed enhanced performance for the TiO2/Ag sample compared to TiO2 nanorods against Methicillin-resistant Staphylococcus aureus after 16 h exposure with a death rate of 84 %.

Synergistic uranium extraction, organic degradation, and electricity generation by a self-driven photoelectrochemical system with TNR/Si PVC photoanode and copper foam cathode

Herein, we develop a self-driven photoelectrochemical system (SDPS) featuring a TiO2 nanorod array (TNR)/Si photovoltaic cell (Si PVC) photoanode and a porous copper foam (CF) cathode for efficient uranium recovery. Under simulated sunlight illumination, this SDPS simultaneously achieves ∼ 99.4 % UO22+ recovery and ∼ 99.2 % sulfamethoxazole (SMX) removal, with observed rate constant (kobs) value of 0.121 min−1 and 0.029 min−1, respectively, and a maximum power density (Pmax) of 0.89 mW·cm−2 when treating complex wastewater of SMX (10 mg·L−1)-UO22+ (10 mg·L−1). The TNR photoanode absorbs short-wavelength light (λ < 412 nm), generating electron-hole pairs, while the rear Si PVC absorbs transmission light, creating a self-bias potential that drives electrons transfer towards CF cathode, continuously generating electrical energy in the external circuit. The retained holes and derived •OH oxidize SMX, breaking UO22+-SMX complexation, while electrons on the CF reduce UO22+ to insoluble tetravalent uranium (U(IV)) species. This SDPS demonstrates robust performance across varying UO22+ (5 ∼ 40 mg·L−1) and SMX (0 ∼ 40 mg·L−1) concentrations, pH ranges (4 ∼ 8), coexisting ions, and different types of uranium-containing wastewaters, maintaining stability over 20 cycles. It achieves ∼ 97.5 % UO22+ extraction and ∼ 99.8 % SMX removal in simulated seawater, with a Pmax of 1.27 mW·cm−2. This work presents a promising resource strategy for uranium extraction.

Enhanced photoelectric properties of TiO2 nanorod arrays through modulation of precursor concentration

This study synthesized titanium dioxide (TiO2) nanorod arrays and investigated their morphology and defect to the photoelectric response by varying the titanium isopropoxide (TTIP) precursor concentration from 0 to 66 mM. The vertically aligned rutile TiO2 nanorods exhibited film thicknesses ranging from 1 to 4.5 μm when the TTIP concentration equaled or exceeded 33 mM. Their rod length and diameter displayed a linear increase with the TTIP concentration. TiO2 arrays synthesized with a TTIP concentration of 33 mM exhibited the highest photoelectric response, measuring 52 μA/cm2 under xenon-lamp irradiation at a bias voltage of 0.8 V (vs. the Ag/AgCl reference). Notably, photoactivity was observed in the visible-light region as well. Photoluminescence spectra indicated a substantial reduction in electron-hole recombination compared to TiO2 arrays prepared from higher TTIP concentrations. X-ray photoelectron spectroscopy and electron paramagnetic resonance analyses confirmed the presence of oxygen vacancies. Time-resolved photoluminescence spectra corroborated an extended electron lifetime, suggesting that surface oxygen vacancies facilitated the separation of photoexcited charge carriers. The presence of oxygen vacancies, combined with the unique array morphology, resulted in enhanced photocurrent density.

Photoelectrocatalytic property and DFT calculations of TiO2 with broadened infrared light absorption by Gd2O3:Er3+

In this paper, erbium-doped gadolinium oxide rare earth oxide nanoparticles (Gd2O3:Er3+) with good light absorption capacity from the visible to the infrared region were prepared by polyol method, and then compounded with TiO2 by hydrothermal method. SEM, TEM, XPS, UV–vis and electrochemical workstation were used to study the morphology, structure, UV–vis light absorption and photoelectrochemical (PEC) properties of Gd2O3:Er3+/TiO2. The results showed that the Gd2O3:Er3+ spherical nanoparticles with a particle size of about 15 nm were uniformly distributed on the surface of the TiO2 nanorod array, and the Gd2O3:Er3+/TiO2 nanocomposites had good light absorption capacity in the infrared region. Furthermore, the photocurrent densities of Gd2O3/TiO2 and Gd2O3:Er3+/TiO2 were 2.08 and 2.75 times higher than those of TiO2, respectively, manifesting that the broadening of infrared light absorption can improve the PEC property of TiO2. Meanwhile, the DFT calculation results showed that the energy band of Gd2O3:Er3+/TiO2 was significantly narrower than that of TiO2, indicating that Gd2O3:Er3+/TiO2 had a redshift phenomenon of UV–vis absorption. The calculation results of state density showed that the f orbital of Gd2O3:Er3+ intersected with the d orbital of TiO2, indicating that there is an electron transfer between Gd2O3:Er3+ and TiO2.

A self-driven solar coupling system with activated carbon felt cathode for resourcefully purifying uranium and organic contaminated water

With the continuous development of nuclear energy, it becomes increasingly important to recover uranium from the radioactive wastewater, in which various organics may combine with uranyl ions (UO22+) to form refractory complexes. Developing highly active cathode materials for uranium reduction is essential to improve the performance of self-driven solar coupling system (SSCS) in treating complex radioactive wastewater. In this study, an activated carbon felt (ACF) cathode is prepared by anodizing carbon felt (CF) in NaOH solution to adjust the surface morphology and functional groups. The ACF is then used in a SSCS combined with a TiO2 nanorods array (TNA) photoanode for the efficient recovery of uranium and the rapid degradation of organic pollutants with simultaneous electricity generation. Compared to CF, the functionalized ACF with oxygen-containing functional groups, provides sufficient sites for UO22+ adsorption and facilitates the charge separation. The SSCS with the ACF cathode exhibits removal ratios of approximately 99.9 % for tetracycline hydrochloride (TCH) and UO22+, with removal rates of ∼ 0.025 and ∼ 0.154 min−1, respectively. In contrast, the SSCS with the CF cathode achieves removal rates of ∼ 0.006 and ∼ 0.026 min−1. Additionally, a maximum power density of 0.94 mW·cm−2 with a fill factor of 23.36 % is achieved. After 20 cycles, the system maintains removal ratios of 99.1 % for TCH and 98.2 % and UO22+. Intensive investigation also reveals that the system functions robustly in treating complex wastewater with a complicated condition of pH, co-exited ions, and various pollutant concentrations. Furthermore, efficient removal of organics and uranium is also achieved from polluted seawater or under real sunlight illumination. This paper presents a simple method to prepare low-cost, highly active and stable cathodes for uranium reduction in an easy-to-operated, energy-saving and economical solar-driven system.

Efficient Photoelectrocatalytic glycerol to dihydroxyacetone synergistic hydrogen production on Co-LDH nanowires modified TiO2 nanorod arrays

The highly selective conversion of glycerol into high value-added products, accompanied by hydrogen generation, through photoelectrocatalytic technology represents an upcycling process that enhances resource utilization and sustainability. In this study, we designed a composite photoanode with a Type II heterojunction structure, Co-LDH(6 h)/TiO2, achieving a high glycerol conversion rate (1083.22 mmol·m−2·h−1) and hydrogen production rate (20.35 mmol·m−2·h−1) while maintaining a high level of DHA selectivity (48 %). Characterization revealed that the engineered Type II heterojunction significantly enhanced visible light absorption and charge separation, thereby reducing electron-hole recombination and improving the efficiency of glycerol conversion and hydrogen production. Furthermore, it was confirmed by in-situ Fourier transform infrared that the Co-LDH(6 h)/TiO2 composites exhibited significant affinity for adsorption intermediate hydroxyl group in glycerol and rapid desorption of DHA, which is a critical factor in achieving high selectivity for the oxidation pathway to DHA. Mechanistic analyses and isotopic labelling indicate that the photogenerated holes in the Co-LDH(6 h)/TiO2 photoanode are the primary active species responsible for the oxidation of glycerol, yielding a spectrum of valuable products. This research provides a novel strategy and in-depth understanding for developing efficient photoanodes for selective oxidation in organic reactions.

Surface-tuning TiO2 NR photoanodes using CoOx interlayers and NiFe-LDH cocatalysts for photoelectrochemical wastewater treatment

Increasing multidrug-resistant pathogenic microbial around the world become a global problem, making it imperative to develop effective methods for bacterial inactivation in wastewater. In this study, we propose a multifunctional photoelectrochemical (PEC) system to successfully disinfect microbial cells and degrade orange (II) dyes. CoOx NP were synthesized by spin-coating onto hydrothermally synthesized TiO2 nanorod arrays followed by electrodeposited NiFe-LDH to develop the NiFe-LDH/CoOx NP-TiO2 NRs. Interestingly, spin-coated CoOx NP-TiO2 NRs exhibited a 1.5-fold enhancement in photocurrent (1.384 mA/cm2) than pristine TiO2 NRs (0.92 mA/cm2). A NiFe-layered double hydroxide (LDH) cocatalysts layer further exhibits the maximum photocurrent density of 1.64 mA/cm2 with IPCE of 84.5% at 1.0 VAg/AgCl at 380 nm. Furthermore, NiFe-LDH/CoOx-TiO2 NR photoanodes were effectually employed for photoelectrochemical bacteria disinfection and organic pollutant removals. With NiFe-LDH/CoOx-TiO2 NR, 99% (120 min) bacterial inactivation and 99% (60 min) orange II dye decomposition efficiency was achieved. Superoxide radicals (−O2•), hydroxyl radicals (HO•), and holes (h+) played a critical role in the PEC degradation systems. Due to the synergy between NiFe-LDH cocatalyst and CoOx interlayer, surface water oxidation reactions were accelerated over NiFe-LDH/CoOx NP-TiO2 NRs. The charge transport process in NiFe-LDH/CoOx NP-TiO2 NRs photoanode-based PEC system was proposed in detail.

Liquid Phase Exfoliation of Few-Layer Non-Van der Waals Chromium Sulfide.

Exfoliation of 2D non-Van der Waals (non-vdW) semiconductor nanoplates (NPs) from inorganic analogs presents many challenges ahead for further exploring of their advanced applications on account of the strong bonding energies. In this study, the exfoliation of ultrathin 2D non-vdW chromium sulfide (2D Cr2S3) by means of a combined facile liquid-phase exfoliation (LPE) method is successfully demonstrated. The morphology and structure of the 2D Cr2S3 material are systematically examined. Magnetic studies show an obvious temperature-dependent uncompensated antiferromagnetic behavior of 2D Cr2S3. The material is further loaded on TiO2 nanorod arrays to form an S-scheme heterojunction. Experimental measurements and density functional theory (DFT) calculations confirm that the formed TiO2@Cr2S3 S-scheme heterojunction facilitates the separation and transmission of photo-induced electron/hole pairs, resulting in a significantly enhanced photocatalytic activity in the visible region.

ZnO/TiO2 heterojunction nanorod array for efficient photoelectrochemical water splitting

This study presents a novel approach utilizing a simple, stable, reproducible CV (Cyclic Voltammetry) electrodeposition method to deposit varying amounts of ZnO onto ordered TiO2 (Rutile) nanorod arrays. Comprehensive investigations were conducted on the morphology, semiconductor band-gap structure of different ZnO/Rutile composites, and their performance in photocatalytic (PC) and photoelectrochemical (PEC) hydrogen production. Results demonstrate that the ZnO/TiO2 photoanodes fabricated in this manner exhibit outstanding PC/PEC hydrogen production capabilities. Particularly noteworthy is the Z/R-15 photoanode, showcasing superior PEC performance with a photocurrent density 3.5 times higher than that of the pristine TiO2 photoanode under equivalent conditions. Furthermore, it was observed that depositing ZnO onto highly crystalline, annealed TiO2 nanorods yields optimal photoelectrical properties. Incorporating oxygen-rich vacancies in ZnO significantly enhances the photoelectrocatalytic performance of TiO2 photoanodes. The CV electrodeposition method offers valuable insights for developing efficient photocatalytic hydrogen production catalysts.

Transition‐Metal‐Doped TiO2 Nanorods with High‐Visible‐Light Response via a Simple Hydrothermal Method

Transition‐metal‐ion doping is an effective method to shorten bandgap and enhance visible‐light absorption of TiO2, but there are still some serious challenges for most doping technologies, such as nonuniform doping, severe lattice damages, metal atoms agglomeration, and inactivated impurities. Herein, a simple and universal hydrothermal method is developed to realize the effective transition‐metal ions doping of TiO2 (including Fe, Co, Mn, Cu, V, and Cr). The photoelectrochemical water splitting performances of Cr‐doped TiO2 nanorods with multifarious Cr ion valence states (Cr3+ or Cr6+ ions), various Cr‐ion concentrations, with or without oxygen vacancy activation are emphatically and systematically studied. Experiments and theoretical calculations demonstrate that the remarkably enhanced carrier separation and injection efficiencies are the key factors to improve the visible‐light photoactivity, benefiting from the homogeneous distribution of impurity atoms and the incorporation of oxygen vacancies. The Cr3+‐ion‐doped TiO2 nanorod arrays with oxygen vacancy activation (Cr3+/Ov–TiO2) displays an impressive incident photon‐to‐electron conversion efficiency of 5.4% at 450 nm visible light, far superior to the pure TiO2 of 0.03%. Furthermore, no obvious photocurrent decay is observed in the Cr3+/Ov–TiO2 photoanode after 12 h continuous light illumination.

Controllable preparation of TiO2 nanorod arrays for enhanced ultraviolet photoresponse performance of Au/TiO2 Schottky junction

The optical and electrical properties of semiconductors depending on the microstructure are crucial for the application in various optoelectronic devices. TiO2 nanorod arrays (NRs) were prepared by hydrothermal method, and the ultraviolet (UV) photoresponse performance of Au/TiO2 NRs Schottky junction device was studied. The morphology, crystal orientation and filminess of TiO2 NRs were modulated by a facile control strategy employing anhydrous ethanol as stabilizer. With the increase of the amount of anhydrous ethanol, the diameter of TiO2 NR gradually expanded and the length increased rapidly. The anhydrous ethanol promotes the growth of TiO2 NRs preferentially in the [001] direction and decreases the oxygen vacancy in the surface of TiO2 NRs. With 10 mL of anhydrous ethanol added, the device displays a high sensitivity (8.93 A/W) to weak 376 nm UV light (0.18 mW/cm2) at a bias of -1V. The highest carrier concentration, the longest electron lifetime, the lowest interfacial charge transfer resistance and series resistance resulted in the best UV photoresponse. The exploration of dynamics process of photogenerated carriers in Schottky junction can help to improve the performance of optoelectronic devices such as photodetectors and solar cells.

Experimental and theoretical studies on the photoelectrocatalytic property of titanium dioxide nanoarrays improved by S,N co-doped graphene quantum dots

In this paper, sulfur and nitrogen co-doped graphene quantum dots (S,N-GQDs) were compounded with titanium dioxide (TiO2) nanorods by chemical surface modification. S,N-GQDs in diameter of 5 nm are uniformly distributed on the surface of TiO2 nanorod arrays. The presence of CS bonds in S,N-GQDs not only broaden the absorption of visible light by GQDs, but also enhanced the visible light absorption of S,N-GQDs/TiO2 composites. The photocurrent densities of S,N-GQDs/TiO2 were 3.66 times that of unmodified TiO2. The calculation results of density functional theory (DFT) showed that the band gap of S,N-GQDs is significantly reduced compared to GQDs, indicating that electrons are more likely to transit to higher energy levels and form more activation sites. Moreover, compared with TiO2, the DFT calculation results of band gap, density of states and charge density difference of S,N-GQDs/TiO2 showed that S,N-GQDs/TiO2 had a wide wavelength of visible light absorption and better electron-hole separation ability, resulting in the superior photoelectrocatalytic property. This research provides favorable analytical value for the development of photocatalysts based on heterostructures.

Precursor-concentration-controlled Morphology of TiO2 Nanorod/Nanoflower Films for Enhanced Photoelectrochemical Water Splitting and Investigating Their Growth Mechanism

Titanium dioxide (TiO2) has been considered as one of the most promising photocatalysts for photoelectrochemical (PEC) water splitting. Therefore, numerous efforts have been devoted to improving its PEC water splitting performance. In this study, TiO2 nanorod/nanoflower (NRF) films with controlled morphology were synthesized on fluorine-doped tin oxide (FTO) glass substrates by following a facile one-step hydrothermal method. The TiO2 NRF films were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectrometer (EDS), and ultraviolet-visible (UV-Vis) spectrophotometer. FE-SEM showed that the TiO2 films are composed of a simultaneous growth of a primary layer of TiO2 nanorod arrays (NRAs) and a second layer of TiO2 nanoflowers (NFs). The proposed growth mechanism highlighted the influence of precursor concentration on nucleation sites, affecting the preferred crystallographic plane growth of rutile TiO2 and nanorod alignment on the FTO substrate. Intriguingly, TiO2 NRF films prepared with 1.0 mL of titanium butoxide exhibited a maximum photocurrent density of 3.58 mA.cm−2 at 1.23 V versus (vs.) the reversible hydrogen electrode (RHE), along with a maximum photoconversion efficiency of 0.69%. The enhanced photocurrent density and photoconversion efficiency were attributed to the optimum thickness in the range of 4.52-7.31 µm, which caused the film to be formed with a unique morphology of the primary layer with well-vertically aligned nanorods and the second layer of flowers consisting of numerous rods stacked on top of one another. This study demonstrates the importance of designing semiconductors with 1D nanorod/3D nanoflower structures as high-performance photoelectrodes for PEC water splitting. Copyright © 2024 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

The stability improvement of photoelectrochemical solar cells with Bi2S3 quantum dots sensitized photoanodes

Bi2S3, Bi2MoO6 and TiO2 composite photoanodes were fabricated using three different preparation routes to improve its photoelectrochemical (PEC) stability. The microstructure of three photoanodes are distinct significantly according to the results of XRD, SEM and TEM. The ordered TiO2 nanorod arrays (NRAs) and thinner Bi2MoO6 sheet crystals in flower-ball structure facilitate carrier transport and suppresses electron-hole recombination efficiently. The results of PEC tests indicate that the photoanode with Bi2MoO6 sheet crystals in flower-ball structure and TiO2 NRAs shows significant enhancement in PEC performance stability due to its ordered microstructure facilitating carrier transport and transfer and also good adherence of photoanode layer on FTO glass substrate. This photoanode in Bi2S3 quantum dots/Bi2MoO6@TiO2 NRAs structure exhibits satisfactory properties, achieving a PEC stability of 86.41% after 48 h.

Internal electric field and oxygen vacancies synergistically boost S-scheme VO/BiOCl-TiO2 heterojunction film for photocatalytic degradation of norfloxacin

Sluggish interfacial dynamics and weak redox properties make the degradation of antibiotics by photocatalysts still a great challenge. Herein, constructing S-scheme heterojunction between BiOCl and TiO2 nanorod arrays (TNA) by hydrothermal method, and the synergistic effect of oxygen vacancies (VO) and Internal Electric Field (IEF) on improving the performance of the photocatalysts was revealed by adjusting the VO. The VO modified BiOCl-TiO2 (VBiTNA) exhibited excellent photocatalytic activities for norfloxacin, achieving a degradation efficiency of up to 90.2 % in just 60 min, and the rate constant was as high as 3.67 × 10-2 min−1. In addition, it also showed great photocatalytic degradation performance of NOR in a wide pH range, complex ionized water environment and real water source. The degradation intermediates and degradation pathway of NOR were predicted with LC-MS technology and Fukui function. Combined with free radical capture, electron paramagnetic resonance, relevant electrochemical testing, and DFT calculations reveals the mechanism of the enhanced photocatalytic performance of VBiTNA. The performance enhancement can be attributed to the expansion of the light absorption range, enhanced adsorption of O2 and effective activation to generate ·O2–, while improving the separation efficiency of electron-hole pairs and maintaining a strong redox capacity. This research focusing on VO and IEF mechanisms will help to advance the rational design of high-performance defective photocatalysts.

Construction of highly active photocatalytic interfaces through light field modulation and photo-deposition of Pd sites

Anchoring noble metal sites through photo-reduction is an effective way to modulate charge distribution on photocatalytic interfaces, thereby enhancing photocatalytic performance. The irradiation field on the exposed surfaces of photocatalysts has an important influence on the morphology and distribution of noble metal sites. However, non-uniform light field derived from the scattering effects of particle-form photocatalysts hinders the well-distributed photo-deposition of noble metal sites. To address this challenge, we proposed a photo-deposition method utilizing the optical fiber coated with photocatalysts. TiO2 nanorod (NR) array was coated on the optical fiber to achieve a well-distributed irradiation filed across the NR array. This resulted in a concentration of the irradiation field primarily within the NR array, maintaining uniformly distributed light intensities throughout. Palladium (Pd) sites dominated by nanoclusters were well distributed on TiO2 NR array utilizing a photo-reduction method. These Pd sites functioned as electron acceptors, facilitating the effective separation and transfer of photo-generated carriers. Consequently, an highly active photocatalytic reaction interface was constructed, demonstrating the accumulation of a substantial concentration of holes and their efficient conversion into hydroxyl radicals (·OH). Notably, hydroxyl radicals with a concentration of 62.6 μM could be generated within 14.4 min. The construction of this efficient photocatalytic interface offers an optimal platform for accelerating photocatalytic reactions and enhancing photocatalytic efficiency.

Improved charge separation by anatase TiO2 nanorod arrays for efficient solid-state PbS quantum-dot-sensitized solar cells

To improve the charge separation and transporting between PbS/TiO2 interface in PbS quantum-dot-sensitized solar cells, a 400 nm length anatase TiO2 nanorod array was successfully prepared by the conversion from ZnO nanorod array immersed in a 75 mM ammonium hexafluorotitanate acid solution. The influence of different immersion time on the microstructure, crystal phase and light absorption of the anatase TiO2 nanorod arrays were systematically studied. The PbS quantum dots (QDs) were deposited on the anatase TiO2 nanorod array via spin-coating-assisted successive ionic layer absorption and reaction (spin-SILAR) procedure using 5 mM PbI2 precursor solution, 5 mM Na2S·9H2O solution and 1% EDT/ethanol (1/99, v/v) solution. The solid-state PbS QD-sensitized anatase TiO2 nanorod array solar cell with the structure of FTO/TiO2 compact layer/PbS QD-sensitized anatase TiO2 nanorod array/spiro-OMeTAD/Au was assembled for the first time, and the champion device exhibited a photoelectric conversion efficiency of 5.47% with an open-circuit voltage of 0.62 V, a short-circuit photocurrent density of 13.71 mA cm-2 and a fill factor of 64.28%.

Self-powered SnSx/TiO2 photodetectors (PDs) with dual-band binary response and the applications in imaging and light-encrypted logic gates

In this work, we report the design and fabrication of self-powered binary response PDs based on II-type heterostructures consisting of SnSx nanoflakes (NFs) and rutile TiO2 nanorod arrays (NRs). The TiO2 NRs effectively block light with wavelengths below 400 nm from reaching SnSx. Under 385 nm light, the photoelectrons in TiO2 recombine with holes in SnSx at the interface due to the energy band bending, resulting in a positive photocurrent. Under 410 nm light, the photoelectrons in SnSx and the photogenerated holes in TiO2 accumulate at the interface, overcoming the interfacial potential barriers induced by the higher Fermi levels of SnSx and inducing a negative photocurrent. Based on the bipolar response, the dual-band imaging capability without external filters and the light-encrypted OR, AND, and NOT logic gates using a single device are demonstrated. This work provides a blueprint for the development of multifunctional self-powered PDs that can simplify system architecture, reduce the energy consumption, and improve accuracy for applications, such as visual systems, light-controlled logic circuits, and encrypted optical communications.