Semiconductor photocatalysis represents a promising and sustainable strategy for addressing global energy shortages and environmental pollution. Among various candidates, Titanium Dioxide (TiO2) has garnered extensive attention due to its excellent chemical stability, non-toxicity, and cost-effectiveness. However, the practical application of bulk TiO2 is severely limited by its low specific surface area and the rapid recombination of photogenerated electron-hole pairs. While constructing nanoporous structures is an effective strategy to overcome these limitations, conventional fabrication methods often suffer from poor substrate adhesion or difficulties in precisely controlling structural parameters. In particular, the thickness of the active porous layer, a critical dimension determining light absorption paths and charge transport distances, has rarely been investigated as an independent variable. To address these challenges, this study proposes a novel composite fabrication strategy combining laser cladding with electrochemical dealloying, aiming to systematically investigate the quantitative structure- property relationship between the thickness of the nanoporous Ti/TiO2 layer and its photoelectrochemical/photocatalytic performance, thereby providing a theoretical basis for the rational design of high-performance photoanodes.
In the experimental phase, Cu-Ti alloy precursor coatings with a specific composition of Cu67Ti33 are fabricated on pure titanium substrates by laser cladding. This high-energy processing method ensures a robust metallurgical bond between the functional layer and the substrate, effectively minimizing interfacial contact resistance compared with physical adhesion methods. Subsequently, the samples undergo selective electrochemical dealloying in a 20wt.% HNO3 electrolyte. In this process, Cu acts as the sacrificial component, while Ti serves as the stable scaffold; as Cu dissolves, the remaining Ti atoms self-assemble into a porous skeleton and are in-situ oxidized to form TiO2. By precisely regulating the dealloying duration (1-40 h), control over the porous layer thickness is achieved, ranging from ~50 μm to over 260 μm. Microscopic morphology and elemental distribution are comprehensively characterized via SEM and EDS. Furthermore, photoelectrochemical properties and photocatalytic activity are rigorously evaluated by instantaneous photocurrent response, Electrochemical Impedance Spectroscopy (EIS), double-layer capacitance (Cdl) measurements, and methyl orange (MO) degradation tests.
Morphological analysis reveals that dealloying generates a distinctive three-dimensional bicontinuous nanoporous network with a hierarchical gradient pore distribution, which facilitates electrolyte infiltration. The porous layer thickness exhibits a non-monotonic trend: it increases initially with time, peaking at ~260.8 μm for the 8-hour sample, before decreasing significantly due to structural delamination and collapse at prolonged durations (16-40 h). The sample dealloyed for 8 h (npT-8 h) demonstrates optimal performance, exhibiting the highest instantaneous photocurrent density (4.54 μA/cm2), the lowest charge transfer resistance (Rct=47.28 Ω·cm2), and the largest electrochemically active surface area (Cdl=5.53 mF/cm2). In contrast, thinner films (e.g., npT-4 h) suffer from insufficient active sites, while thicker, delaminated films show increased recombination losses. Consequently, npT-8 h achieves a 61% MO degradation rate within 180 min, with a pseudo-first-order rate constant (k=0.005 29 min-1) approximately 4.3 times that of the npT-4 h sample. The superior performance of npT-8 h is attributed to a synergistic balance achieved at this specific thickness (~260.8 μm), representing an optimal equilibrium where charge separation/transport efficiency and surface reactivity are effectively balanced, further assisted by the light-trapping effect of the porous network. This work demonstrates the feasibility of the laser cladding-dealloying route for fabricating robust porous electrodes and clarifies the underlying mechanism of thickness-dependent performance optimization.
Key words
laser cladding /
electrochemical dealloying /
porous Ti/TiO2 photoanodes /
porous layer thickness /
thotocatalytic performance
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
References
[1] MILANI M, MAZZANTI M, MAGNACCA G, et al.A Novel Hydrothermal CdS with Enhanced Photocatalytic Activity and Photostability for Visible Light Hydrogenation of Azo Bond: Synthesis and Characterization[J]. Nanomaterials, 2023, 13(3): 413.
[2] PENG L Y, LIU J X, LI Z Y, et al.One-Step Thermal Polymerization Synthesis of Nitrogen-Rich G-C3N4 Nanosheets Enhances Photocatalytic Redox Activity[J]. RSC Advances, 2022, 12(52): 33598-33604.
[3] SU T M, MEN C Z, CHEN L Y, et al.Sulfur Vacancy and Ti3C2Tx Cocatalyst Synergistically Boosting Interfacial Charge Transfer in 2D/2D Ti3C2Tx/ZnIn2S4 Heterostructure for Enhanced Photocatalytic Hydrogen Evolution[J]. Advanced Science, 2022, 9(4): 2103715.
[4] AGUINACO A, MÁNUEL J M, BLANCO E, et al. Fe3O4-TiO2 Thin Films in Solar Photocatalytic Processes[J]. Materials, 2022, 15(19): 6718.
[5] COVALIU-MIERLĂ C I, MATEI E, STOIAN O, et al. TiO2-Based Nanofibrous Membranes for Environmental Protection[J]. Membranes, 2022, 12(2): 236.
[6] DEHGHANI M T, DELNAVAZ M.UV-Light-Responsive Ag/TiO2/PVA Nanocomposite for Photocatalytic Degradation of Cr, Ni, Zn, and Cu Heavy Metal Ions[J]. Scientific Reports, 2024, 14: 5195.
[7] KALANTARI BOLAGHI Z, RODRIGUEZ-SECO C, YURTSEVER A, et al.Exploring the Remarkably High Photocatalytic Efficiency of Ultra-Thin Porous Graphitic Carbon Nitride Nanosheets[J]. Nanomaterials, 2024, 14(1): 103.
[8] KAMBLE G S, NATARAJAN T S, PATIL S S, et al.BiVO4 as a Sustainable and Emerging Photocatalyst: Synthesis Methodologies, Engineering Properties, and Its Volatile Organic Compounds Degradation Efficiency[J]. Nanomaterials, 2023, 13(9): 1528.
[9] LÜ X J, HUANG F Q, WU J J, et al.Intelligent Hydrated- Sulfate Template Assisted Preparation of Nanoporous TiO2 Spheres and Their Visible-Light Application[J]. ACS Applied Materials & Interfaces, 2011, 3(2): 566-572.
[10] ZHANG J Y, WANG C, SHI X G, et al.Preparation and Photocatalytic Performance Study of TiO2-TMP Composites under Effect of Crystal Structure Modulation[J]. Materials, 2025, 18(11): 2623.
[11] CHEN Y A, XIANG Z Y, WANG D S, et al.Effective Photocatalytic Degradation and Physical Adsorption of Methylene Blue Using Cellulose/GO/TiO2 Hydrogels[J]. RSC Advances, 2020, 10(40): 23936-23943.
[12] CAI H R, YANG B, HOU J, et al.Scalable Synthesis of PtAu Nanoalloy-Decorated Hydrogenated TiO2 for High-Efficiency Indoor Formaldehyde Photodegradation[J]. Nanomaterials, 2025, 15(9): 683.
[13] 项一侯, 王景辉, 方永涌, 等. 多孔Ti基电极的激光熔覆-脱合金复合制备工艺及其光催化性能研究[J]. 中国激光, 2025, 52(12): 73-83.
XIANG Y H, WANG J H, FANG Y Y, et al.Preparation and Photocatalytic Performance of Porous Ti-Based Electrodes via Laser Cladding and Dealloying[J]. Chinese Journal of Lasers, 2025, 52(12): 73-83.
[14] WANG J Q, WANG J T, LV Z W, et al.A Study of Electroplated Nanoporous Copper Using Aberration- Corrected Transmission Electron Microscopy[J]. Nanomaterials, 2024, 14(6): 487.
[15] WEN H, HANG L F, LIANG L B, et al.Rapid Synthesis of Monodispersed Au-Ag Alloy Nanosponges Using Selective Laser Melting and Dealloying for Sensitive Near-Infrared Surface-Enhanced Raman Scattering[J]. Nanotechnology, 2022, 33(2): 025604.
[16] HE S W, LI J H, XU Y C, et al.Deep Eutectic Solvent- Assisted Synthesis of a 3D Nanoporous Surface on Zr-Based Amorphous Alloy[J]. Journal of Alloys and Compounds, 2022, 903: 163949.
[17] QIAN H X, MU X B, LI K Y, et al.Nanoporous Copper Sonocatalysts Prepared by Dealloying Cu-Al-Ti Amorphous Ribbons[J]. Materials Science and Technology, 2020, 36(10): 1083-1091.
[18] AN Z Y, SUN S Y, DONG B H.An Investigation Using DFT into the Impact of Hydrogen on Oxygen Migration Processes during Aluminum Anodization[J]. RSC Advances, 2024, 14(17): 11668-11675.
[19] GE C, LI Y C, SONG H Y, et al.Anisotropic Carrier Dynamics and Laser-Fabricated Luminescent Patterns on Oriented Single-Crystal Perovskite Wafers[J]. Nature Communications, 2024, 15: 914.
[20] NG C, YAP L W, ROBERTS A, et al.Black Gold: Broadband, High Absorption of Visible Light for Photochemical Systems[J]. Advanced Functional Materials, 2017, 27(2): 1604080.
[21] LIMARGA A M, WILKINSON D S, WEATHERLY G C.Modeling of Oxidation-Induced Growth Stresses[J]. Scripta Materialia, 2004, 50(12): 1475-1479.
[22] ERLEBACHER J, AZIZ M J, KARMA A, et al.Evolution of Nanoporosity in Dealloying[J]. Nature, 2001, 410(6827): 450-453.
[23] YE X L, LU N, LI X J, et al.Primary and Secondary Dealloying of Au(Pt)-Ag: Structural and Compositional Evolutions, and Volume Shrinkage[J]. Journal of the Electrochemical Society, 2014, 161(12): C517-C526.
[24] PILLAI M M, KALIDAS N, ZHAO X Y, et al.Biomass- Based Silicon and Carbon for Lithium-Ion Battery Anodes[J]. Frontiers in Chemistry, 2022, 10: 882081.
[25] SONG D D, CHEN Z, CUI P, et al.NH3-Treated WO3 as Low-Cost and Efficient Counter Electrode for Dye-Sensitized Solar Cells[J]. Nanoscale Research Letters, 2015, 10(1): 16.
[26] BARSOUKOV E, MACDONALD J R.Impedance Spectroscopy: Theory, Experiment, and Applications[M]. Hoboken: Wiley, 2005.
[27] WANG C C, TSANG A, SANG Y J, et al.The Microstructural Dependence of Ionic Transport in Bi-Continuous Nanoporous Metal[J]. Acta Materialia, 2024, 276: 120134.
[28] WAHBA R H, EL-SONBATI A Z, DIAB M A, et al. Electrochemical Corrosion Performance of N80 Steel in Acidized 10% HCl Medium Using 4-Methyl-1-Phenyl- 3-(p-Tolyldiazenyl)-2, 3-Dihydro-1H-Pyrrol-2-Ol[J]. Heliyon, 2025, 11(3): e42317.
[29] JENILA T J, INFANCY W T, RATHIKHA R, et al.Unraveling the Role of MXene (Ti3C2Tx) Integrated Cu-Doped WO3 Nanocomposites via Co-Precipitation Technique for Enhanced Supercapacitor Performance[J]. Scientific Reports, 2025, 15: 25007.
[30] LIU K Y, SHEN H, SUN Z Y, et al.Transient Pulsed Discharge Preparation of Graphene Aerogel Supports Asymmetric Cu Cluster Catalysts Promote CO2 Electroreduction[J]. Nature Communications, 2025, 16: 1203.
[31] HAN J, TRI PHAM N B, OH K, et al. Robust Biobased Membrane: Self-Entangled Cellulose Nanofibrils-ZnO- Ag Composite with High Photocatalytic Performance for Efficient Dye-Contaminated Water Treatment[J]. ACS Omega, 2024, 9(6): 7143-7153.
[32] LIN Z, YU X K, ZHAO Z J, et al.Controlling Crystallization in Covalent Organic Frameworks to Facilitate Photocatalytic Hydrogen Production[J]. Nature Communications, 2025, 16: 1940.
[33] PANCIELEJKO A, RZEPNIKOWSKA M, ZALESKA- MEDYNSKA A, et al.Enhanced Visible Light Active WO3 Thin Films Toward Air Purification: Effect of the Synthesis Conditions[J]. Materials, 2020, 13(16): 3506.
[34] FUJISHIMA A, ZHANG X T, TRYK D A.TiO2 Photocatalysis and Related Surface Phenomena[J]. Surface Science Reports, 2008, 63(12): 515-582.
Funding
The National Key Research and Development Program of China (2023YFB4606000); The National Natural Science Foundation of China (U22A20199); Zhejiang Provincial Natural Science Foundation of China (LQN26E010026)
PDF(10398 KB)
