Chemical coating method for strong-alkali-resistant broadband infrared window
The chemical deposition method solves the problems of expensive equipment, complex processes, and poor adhesion in preparing strong alkali resistant broadband infrared window metal thin films, achieving efficient and low-cost high-performance film preparation, enhancing infrared signal detection effects and expanding application range.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-09
- Publication Date
- 2026-05-15
AI Technical Summary
Existing technologies for preparing metal thin films with strong alkali resistant broadband infrared windows suffer from problems such as expensive equipment, complex processes, long processing times, poor adhesion, easy contamination, and limited SEIRA enhancement effects.
A chemical plating method, including pretreatment, crystal nucleation and chemical plating steps, is used to prepare high-adhesion, low-cost metal films suitable for a variety of metals using conventional chemical reagents and simple heating devices.
It enables efficient, rapid, and low-cost preparation of high-performance metal thin films with strong adhesion, avoids organic pollution, enhances infrared signal detection, and expands the application range to all pH environments.
Smart Images
Figure CN122039031A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrochemical technology, and particularly relates to a chemical coating method for a strong alkali resistant broadband infrared window. Background Technology
[0002] Electrocatalysis has important applications in energy, environment, and chemical engineering. Understanding the reaction processes at the electrode / solution interface is crucial for optimizing electrocatalytic performance. Electrochemical surface-enhanced infrared spectroscopy (ATR-SEIRAS) has attracted widespread attention due to its ability to characterize interfacial molecular structures in situ with high sensitivity. However, traditional ATR-SEIRAS techniques are limited in the low-frequency region (1200-400 cm⁻¹). -1 It is difficult to detect and is not applicable under strongly alkaline conditions.
[0003] To extend ATR-SEIRAS technology to a wider range of electrochemical systems, including strong acids and bases, researchers have developed novel composite infrared optical windows. These windows typically use a silicon wafer as a substrate, with a corrosion-resistant conductive or semi-conductive barrier layer (such as boron-doped diamond (BDD), titanium dioxide (TiO2), or indium tin oxide (ITO)) covering its surface. This protects the silicon substrate from corrosion for broadband detection while also serving as a conductive substrate for electrochemical research. However, fabricating metal thin films with good conductivity, SEIRA activity, and stability on such composite windows presents a challenge.
[0004] Currently, physical vapor deposition (PEV) methods (such as evaporation and sputtering) are mainly used to deposit metal thin films on composite windows. This method has the following obvious disadvantages: (1) The equipment is expensive, the process is complex and time-consuming (usually more than 3-4 hours); (2) The deposited film has weak adhesion to substrates such as BDD and is easy to fall off during electrochemical cycling; (3) The film surface is easily contaminated by organic matter such as hydrocarbons, which is difficult to completely remove in subsequent electrochemical treatment, and may introduce interfering peaks or cause spectral distortion (such as the generation of bipolar peaks) in the infrared spectrum; (4) The SEIRA enhancement effect of the film is limited.
[0005] Therefore, there is an urgent need to develop a simple, low-cost, and efficient alternative method to prepare high-performance metal thin films on composite infrared optical windows. Summary of the Invention
[0006] The purpose of this invention is to provide a chemical coating method for a strong alkali-resistant broadband infrared window, aiming to solve the problems mentioned in the background art.
[0007] The present invention is implemented as follows: a chemical coating method for a broadband infrared window resistant to strong alkali includes the following steps: Step 1: Preprocessing; First, the composite infrared window was cleaned with a mixture of H2SO4 and H2O2, and then rinsed with a large amount of ultrapure water. Step 2: Crystal nucleus growth; The bright surface of the composite infrared window is immersed in a metal seed solution and treated at room temperature for 2 minutes to grow crystal nuclei; the metal seed solution is a mixture of hydrofluoric acid (HF) solution and metal precursor solution; Step 3: Chemical plating; The composite infrared window is clamped up, rinsed with ultrapure water, and then placed in an environment of 40-60℃ to contact a mixture of metal precursor solution and N2H4∙H2O, where a metal layer is deposited within a set time.
[0008] In a further technical solution, in step 1, the volume ratio of H2SO4 to H2O2 in the H2SO4 and H2O2 mixture is 7:3.
[0009] In a further technical solution, the composite infrared window used in step 1 is a micro-machined silicon wafer with a surface-covered barrier layer for protection.
[0010] In a further technical solution, the barrier layer is titanium dioxide (TiO2), boron-doped diamond (BDD), indium tin oxide (ITO), indium zinc oxide (IZO), or titanium nitride (TiN).
[0011] In a further technical solution, in step 2, the metal precursor in the metal seed solution is HAuCl4, PdCl2, or CuSO4·5H2O.
[0012] In a further technical solution, the time set in step 3 is 8-10 minutes.
[0013] In a further technical solution, in step 3, the plating solution used for Au plating is 0.0075 M NaAuCl4 + 0.025 M NH4Cl + 0.075 M Na2SO3 + 0.025 M Na2S2O3·5H2O, and 25 μL of N2H4∙H2O is added to 2 mL of this plating solution for chemical plating.
[0014] In a further technical solution, in step 3, the plating solution used for plating Pt is 0.01 M K2PtCl6 + 0.67 M NH3∙H2O + 0.06 M N2H4∙H2O.
[0015] In a further technical solution, in step 3, the plating solution used for Pd plating is: Solution A: 0.01 M HCl + 0.02 M PdCl2 + 0.15 M anhydrous ethylenediamine; Solution B: 2 M NH3·H2O + 0.1 M N2H4∙H2O; When using, take 1 mL of solution A and 2 mL of solution B and mix them.
[0016] In a further technical solution, in step 3, the plating solution used for Ni plating is 5 mM NiSO4·6H2O + 0.25M N2H4∙H2O, and the pH is adjusted to 11.5 with ammonia.
[0017] The present invention provides a chemical coating method for a strong alkali-resistant broadband infrared window, the beneficial effects of which include: (1) High efficiency and speed: The entire chemical plating process only takes about 20 minutes, which is more than 10 times shorter than the traditional evaporation / sputtering method (3-4 hours or more), greatly improving the preparation efficiency.
[0018] (2) Low cost: It does not require expensive and complex vacuum coating equipment. It can be completed using only conventional chemical reagents and simple heating devices, which significantly reduces the preparation cost.
[0019] (3) Excellent film performance: The adhesion between the metal film obtained by chemical plating and composite substrates such as BDD is extremely strong, and it remains intact after hundreds of electrochemical cycles, with stability far exceeding that of physically deposited films. At the same time, the film surface is clean, avoiding the organic pollution problems common in physical deposition.
[0020] (4) Significant enhancement effect: The island-shaped metal nanostructure formed by chemical plating can generate a strong electromagnetic field enhancement effect. Its surface enhancement factor for infrared signals is at least 3 times that of the vapor-deposited film, which significantly improves the signal-to-noise ratio of ATR-SEIRAS detection.
[0021] (5) Wide applicability and versatility: This method can be applied to the preparation of various metal thin films such as Au, Pt, Pd, Ni, and Cu, and has excellent versatility. The prepared broadband infrared window can work stably in the entire pH range, which greatly expands the application scenarios of ATR-SEIRAS technology.
[0022] (6) Simple and controllable process: By adjusting parameters such as seed solution composition, plating solution formulation and reaction time, the thickness, morphology and performance of the film can be easily controlled, and the process repeatability is good. Attached Figure Description
[0023] Figure 1 To compare the ATR-SEIRAS spectra of Au electrodes deposited by vapor deposition and electroless plating in CO-saturated 0.1 M HClO4; Figure 2Electrochemical behavior of Au electrodes prepared by vapor deposition and electroless plating in Ar-saturated 0.1 M HClO4 solution (where a is vapor deposition and b is electroless plating). Figure 3 The ATR-SEIRAS spectra of CO saturated adsorption of Au, Pt and Pd metals after electroless plating in 0.1 M HClO4 and 1.0 M KOH are shown (where a is Au, b is Pt and c is Pd). Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0025] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.
[0026] An embodiment of the present invention provides a chemical coating method for a strong alkali-resistant broadband infrared window, comprising the following steps: Step 1: Preprocessing; First, the composite infrared window was cleaned with a mixture of H2SO4 and H2O2 (volume ratio 7:3), and then rinsed with a large amount of ultrapure water. Step 2: Crystal nucleus growth; The bright surface of the composite infrared window is immersed in a metal seed solution (HF + metal precursor) and treated at room temperature for 2 minutes to grow crystal nuclei. The metal seed solution can be 0.6 M HF + 1 mM HAuCl4, 0.6 M HF + 2 mM PdCl2 + 0.01 M NaCl, or 0.6 M HF + 3.15 mM CuSO4·5H2O, depending on the metal being grown.
[0027] Step 3: Chemical plating; The composite infrared window is clamped up, rinsed with ultrapure water, and then placed in an environment of 40-60℃ to contact with a metal precursor solution and a chemical plating solution of N2H4∙H2O. A metal layer is deposited within a set time (usually 8-10 minutes). Depositable metals include Au, Pt, Pd, Ni, Cu, etc.
[0028] In this embodiment of the invention, the deposited metal film can be used for ATR-SEIRAS testing after electrochemical cleaning.
[0029] In a preferred embodiment of the present invention, in step 1, the composite infrared window used is a micro-machined silicon wafer protected by a surface covering barrier layer (including titanium dioxide TiO2, boron-doped diamond BDD, indium tin oxide ITO, indium zinc oxide IZO, and titanium nitride TiN).
[0030] In a preferred embodiment of the present invention, the electroless plating solution for Au plating is 0.0075 M NaAuCl4 + 0.025 M NH4Cl + 0.075 M Na2SO3 + 0.025 M Na2S2O3·5H2O, and 25 μL of N2H4∙H2O is added to 2 mL of this plating solution for electroless plating.
[0031] The chemical plating solution used for Pt plating is 0.01 M K2PtCl6 + 0.67 M NH3∙H2O + 0.06 M N2H4∙H2O.
[0032] The electroless plating solution used for Pd plating is: Solution A: 0.01 M HCl + 0.02 M PdCl2 + 0.15 M anhydrous ethylenediamine; Solution B: 2 M NH3∙H2O + 0.1 M N2H4∙H2O; When using, take 1 mL of solution A and 2 mL of solution B and mix them.
[0033] The chemical plating solution used for Ni plating is 5 mM NiSO4·6H2O + 0.25 M N2H4∙H2O, with the pH adjusted to 11.5 using ammonia.
[0034] In this embodiment of the invention, the thickness of the electroless plated metal film is approximately 60-100 nm. The effects of electroless plating and vapor deposition are compared using an Au thin-film electrode. Taking the adsorption of carbon monoxide on Au as an example... Figure 1 As shown, the ATR-SEIRAS signal on electroless Au is more than three times that of the vapor deposition method, indicating that the thin film obtained by this electroless deposition method has excellent enhancement effect.
[0035] Figure 2 As can be seen, the electrochemical behavior of vapor-deposited Au is normal, while that of electroless-deposited Au does not fall off after 100 electrochemical scans, whereas that of vapor-deposited Au dissolves and falls off after 100 scans. This indicates that the adhesion and stability of electroless-deposited metal films are superior to those of vapor-deposited metal films.
[0036] The ATR-SEIRAS spectra of CO saturated adsorption in 0.1 M HClO4 and 1.0 M KOH for electroless plating of Au, Pt, and Pd are shown below. Figure 3As shown, the metal thin films obtained by this method are applicable to a wide pH range from strong acids to strong bases, and the method is universal and can be extended to deposit various different metal thin films.
[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A chemical coating method for a strong alkali-resistant broadband infrared window, characterized in that, Includes the following steps: Step 1: Preprocessing; First, the composite infrared window was cleaned with a mixture of H2SO4 and H2O2, and then rinsed with a large amount of ultrapure water. Step 2: Crystal nucleus growth; The bright surface of the composite infrared window is immersed in a metal seed solution and treated at room temperature for 2 minutes to grow crystal nuclei; the metal seed solution is a mixture of HF solution and metal precursor solution. Step 3: Chemical plating; The composite infrared window is clamped up, rinsed with ultrapure water, and then placed in an environment of 40-60℃ to contact a mixture of metal precursor solution and N2H4∙H2O, where a metal layer is deposited within a set time.
2. The chemical coating method for a strong alkali-resistant broadband infrared window according to claim 1, characterized in that, In step 1, the volume ratio of H2SO4 to H2O2 in the H2SO4 and H2O2 mixture is 7:
3.
3. The chemical coating method for a strong alkali-resistant broadband infrared window according to claim 1, characterized in that, In step 1, the composite infrared window used is a micro-machined silicon wafer with a surface-covered barrier layer for protection.
4. The chemical coating method for a strong alkali-resistant broadband infrared window according to claim 3, characterized in that, The barrier layer is titanium dioxide (TiO2), boron-doped diamond (BDD), indium tin oxide (ITO), indium zinc oxide (IZO), or titanium nitride (TiN).
5. The chemical coating method for a strong alkali-resistant broadband infrared window according to claim 1, characterized in that, In step 2, the metal precursor in the metal seed solution is HAuCl4, PdCl2, or CuSO4·5H2O.
6. The chemical coating method for a strong alkali-resistant broadband infrared window according to claim 1, characterized in that, In step 3, the set time is 8-10 minutes.
7. The chemical coating method for a strong alkali-resistant broadband infrared window according to claim 1, characterized in that, In step 3, the depositable metals include Au, Pt, Pd, Ni, and Cu.