Gradient composite graphene electrolysis electrode plate and in-situ preparation method thereof

Abstract

The invention provides a gradient composite graphene electrolysis electrode plate and an in-situ preparation method thereof. The electrode plate comprises a metal conductive base material (such as titanium alloy), a porous ceramic skeleton layer (Al2O3-40% ZrO2, the porosity of which is 30 + / -5%), a chemical copper plating layer for filling pores, an electroplated nickel-ruthenium alloy catalytic layer (Ni: Ru = 9: 1) and 3-5 graphene functional layers (ID / IG is less than or equal to 0.08) grown in situ, wherein the porous ceramic skeleton layer (Al2O3-40% ZrO2) is laser-cladded on the surface of the porous ceramic skeleton layer (Al2O3-40% ZrO2). The preparation method comprises the following steps: performing laser cladding on a ceramic skeleton, wherein the power density is 300-500W / mm < 2 >, and sintering at 1600 DEG C to form metallurgical bonding; gradient plating: electroless copper plating (containing nano-diamond enhancement) and pulse electroplating of Ni Ru (duty ratio is 1: 5); and performing directional CVD growth: after reducing the catalyst layer by H2 at 1050 DEG C, introducing CH4 / H2 (the volume ratio is 1: 4) in a pulse manner, and realizing full coverage of the inner wall of the mesh by vortex air intake. The technical effects are as follows: (1) the overpotential of chlorine evolution in saturated salt water at 80 DEG C is as low as 268mV (1A / cm < 2 >); (2) strong acid environment service life gt; the time is 100 thousand hours (12 times that of the national standard); (3) the production cost is lt; and 620 / m < 2 > (90% lower than that of a traditional ruthenium-iridium coating). The problems of graphene transfer damage and special-shaped electrode covering are solved.

Description

Technical Field

[0001] The present invention belongs to the field of industrial electrochemical technology, and specifically relates to a graphene composite electrode plate suitable for strong corrosion / high-temperature electrolysis scenarios, which realizes transfer-free growth of graphene through a ceramic-metal composite substrate and pulsed CVD technology. Background Art

[0002] 1. Technical Pain Point Analysis

[0003] Electrode type defect root cause Precious metal coated electrodes <![CDATA[Cost > $5000 / m 2 , coating spall life < 1 year]]> Wear and interface thermal expansion coefficient mismatch graphite electrodes Brittle fracture (flexural strength < 50MPa) Anisotropic structural defects CVD transferred graphene Breakage rate>40%, interface resistance increases 10 times Polymer residue and mechanical stress damage

[0004] 2. Limitations of existing solutions

[0005] Ceramic-based patent CN117757123A: only solves the corrosion protection of the tank body and does not involve the design of the electrode functional layer;

[0006] Metal-based patent CN105261778A: Creep of the metal substrate at high temperature (>800°C) causes graphene wrinkling. Summary of the Invention

[0007] 1. Technical Issues

[0008] Collaborative solution:

[0009] 1. Substrate corrosion and interface failure in strong acid / high temperature environments;

[0010] 2. Full graphene coverage of special-shaped electrodes (mesh / curved surface);

[0011] 3. Yield and cost control of industrial production.

[0012] 2. Technical Solution

[0013] Composite electrode structure (such as attached Figure 1 ):

[0014] 1. Metal conductive substrate (bottom layer): copper / titanium alloy, thickness 2-10mm, provides current conduction;

[0015] 2. Ceramic reinforced skeleton (middle layer): Al2O3-ZrO2 porous ceramic (porosity 30±5%), flexural strength ≥800MPa; 3. Metal catalyst layer (transition layer):

[0016] Chemical copper plating (0.5-1μm) fills the ceramic pores;

[0017] Electroplating nickel-ruthenium alloy (Ni:Ru=9:1, 1-2μm) to provide CVD catalytic sites;

[0018] 4. Graphene functional layer (surface layer): 3-5 layers of AB stacked graphene (Raman 2D peak half-height width ≤ 35cm -1 ).

[0019] 3. Steps:

[0020] 1. Substrate composite:

[0021] Laser cladding of ceramic layer (Al2O3-40% ZrO2) on the surface of metal substrate with a thickness of 200-500μm;

[0022] Sintered at 1600℃ under argon protection to form a metallurgical bonding interface.

[0023] 2. Gradient coating:

[0024] Craftsmanship parameter Function Chemical copper plating <![CDATA[EDTA-Na230g / L,pH=12.8,60℃]]> Pore ​​filling (coverage > 99.5%) Pulse plating Ni Ru <![CDATA[Frequency 1000Hz, duty cycle 1:5, RuSO4 8g / L]]> Inhibits dendrites and increases catalytic activity by 3 times

[0025] 3. Directed CVD growth:

[0026] Crystal plane reorganization: 1050℃ / H2 reduction for 2h → the (111) crystal plane of the NiRu layer is greater than 85% (EBSD verification);

[0027] Pulsed carbon source: CH4 / H2=1:4 (v / v), pulse period 10s (2s on / 8s off) → control of graphene layer number accuracy ±0.5 layer;

[0028] Airflow design: The mesh electrode adopts vortex air intake (Reynolds number Re=2500) to ensure that the flow rate in the hole is greater than 120% of the center area.

[0029] 4. Core Process Innovation

[0030] (1) Gradient composite structure design

[0031] 1. Five-layer functional architecture

[0032]

[0033] Structural advantages:

[0034] Corrosion blocking: Ceramic skeleton blocks electrolyte penetration (corrosion rate ↓99%);

[0035] Stress matching: thermal expansion coefficient gradient transition (metal 9×10 -6 / ℃→ceramic8.5×10 -6 / ℃), inhibiting interface delamination.

[0036] (2) Core process innovation

[0037] 2. Catalytic layer directional control technology

[0038] mechanism:

[0039] High carbon solubility in nickel (0.9 at%) → carburization and carbon precipitation to form multilayer graphene;

[0040] Ruthenium's low-temperature catalytic activity (800-900°C) → reduces the risk of thermal shock in ceramics;

[0041] parameter:

[0042] Pulse plating duty cycle 1:5 → inhibits dendrites (porosity < 0.1%);

[0043] H2 partial pressure 50±5Pa→removal of oxides to ensure crystal plane reorganization.

[0044] 3. Control of graphene growth dynamics

[0045]

[0046] 5. Technical Effect Data

[0047] (1) Performance comparison

[0048]

[0049] (2) Cost Analysis

[0050]

[0051] Compared to Ruthenium Iridium coating ($5,000 / m 2 ) decreased by 87.6%

[0052] The advantages of this application also lie in the addition of an intermediate layer process of electroplating nickel / ruthenium:

[0053] 1. Optimizing the catalytic mechanism of graphene growth

[0054] The surface adsorption catalysis of the nickel layer. Nickel metal has a high carbon solubility characteristic (~0.9at%) and can adsorb a large amount of carbon atoms to form a solid solution during the high-temperature stage of CVD (1000-1050℃); during the cooling process, supersaturated carbon atoms precipitate from the inside of the nickel matrix to form a continuous graphene film.

[0055] Compared with pure copper (the dissolved carbon content is only 0.001at%), nickel's carburization-carbon deposition mechanism is more likely to form multi-layer graphene (3-10 layers), thereby improving the mechanical strength and conductive uniformity of the electrode.

[0056] Synergistic catalysis and stability of the ruthenium layer: Ruthenium (Ru) has higher catalytic activity and can achieve graphene growth under low temperature conditions (800-900°C), reducing the risk of thermal stress cracking of the ceramic substrate.

[0057] Acid resistance of ruthenium (corrosion rate <0.01μA / cm in pH <3 environment) 2 ) can protect the underlying metal from being penetrated by the electrolyte.

[0058] 2. Enhance interface bonding strength and structural stability

[0059] Gradient transition layer design: Chemical copper plating bottom layer (0.5-2μm): fills the micropores on the ceramic surface and provides a uniform conductive base.

[0060] Electroplated nickel / ruthenium intermediate layer (1-3μm): Pulse electroplating technology (duty cycle 1:5) is used to inhibit dendrite growth and form a dense non-porous structure (porosity <0.1%) to avoid electrolyte penetration and substrate corrosion.

[0061] Inhibit interface diffusion and oxidation: The nickel layer can block the diffusion of copper atoms into the graphene layer during the high-temperature CVD process, preventing the formation of copper oxide impurities (such as Cu2O) and avoiding the decrease of graphene electron mobility.

[0062] 3. Optimizing electrocatalytic activity and conductivity

[0063] Reduce interfacial contact resistance (ICR)

[0064] The interface contact resistance between the nickel / ruthenium interlayer and graphene is only 9.94 mΩ·cm 2 (Bare titanium alloy is 100-200mΩ·cm 2 ), reducing electrolysis energy consumption.

[0065] Mechanism: The metal intermediate layer provides a continuous conductive path to compensate for the contact defects of the graphene edge8.

[0066] Improve the efficiency of chlorine / oxygen evolution reactions

[0067] The high catalytic activity of ruthenium reduces the overpotential of chlorine evolution by 120 mV (1 A / cm 2 current density), suitable for chlor-alkali industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 : The composite electrode structure of the present invention;

[0069] Figure 2 : Planar graphics of graphene electrolysis electrode plate; 1. graphene electrolysis electrode plate, 2. wiring nostril of graphene electrolysis electrode plate;

[0070] Figure 3 : SEM image of the graphene electrode obtained in Example 1 (showing complete coverage);

[0071] Figure 4 : Schematic diagram of mesh CVD (chemical vapor deposition) airflow optimization. DETAILED DESCRIPTION

[0072] Example 1 (chlor-alkali industry flat electrode)

[0073] Structure: Titanium plate (5mm) + Al2O3-ZrO2 ceramic layer (300μm) + NiRu coating (1.5μm)

[0074] Process:

[0075] 1. Laser cladding ceramics: power 3kW, scanning speed 10mm / s, powder feeding rate 25g / min;

[0076] 2. Chemical copper plating: The plating solution contains nanodiamond (50nm, 0.5g / L) to improve the bonding strength;

[0077] 3.CVD growth:

[0078] After preheating at 1050 °C, CH4 was pulsed in (peak flow rate 15 L / min);

[0079] After deposition, the temperature was gradually decreased (10°C / min) to 600°C.

[0080] performance:

[0081] In saturated NaCl solution (80°C):

[0082] Chlorine evolution overpotential 268mV (1A / cm 2 ), 162 mV lower than that of the DSA electrode;

[0083] Accelerated lifespan > 100,000 hours (12 times the national standard requirement).

[0084] Example 2 (PEM electrolyzer mesh electrode)

[0085] Structure: 316L stainless steel mesh (pore size 2mm) + Si3N4 ceramic layer (200μm) + NiRu coating (1μm)

[0086] Innovative technology:

[0087] Mesh CVD airflow optimization: (see attached Figure 4 )

[0088] In-situ quality monitoring: Laser interferometer provides real-time coverage feedback (deposition is terminated when >98%).

[0089] Effect:

[0090] Current distribution uniformity (standard deviation σ<0.5%);

[0091] At 1.8V@2A / cm 2 Under these conditions, the hydrogen production efficiency is 86.7% (81.2% for traditional electrodes).

[0092] Technological advantages

[0093] 1. Global Performance Comparison

[0094] index The present invention Pure ceramic-based solution Pure metal-based solutions Strong acid corrosion rate 0.00003mm / year 0.001mm / year 0.02mm / year Interface resistance <![CDATA[1.8mΩ·cm 2 ]]> <![CDATA[3.5mΩ·cm 2 ]]> <![CDATA[2.5mΩ·cm 2 ]]> Thermal shock stability (ΔT=500℃) >90 cycles >100 cycles <10 cycles Production costs <![CDATA[$620 / m 2 ]]> <![CDATA[$1050 / m 2 ]]> <![CDATA[$480 / m 2 ]]>

[0095] 2. Patent barrier design

[0096] Structural barriers: The composite substrate has a three-level gradient structure of "metal-ceramic-metal catalyst layer" (avoiding the single-layer metal base of CN105261778A);

[0097] Process barriers:

[0098] Laser cladding ceramic layer combined with electroplated catalytic layer (different from the pure coating in CN117757123A);

[0099] Pulsed CVD+ eddy current air intake (breaking the bottleneck of special-shaped electrode coverage).

Claims

1. A gradient composite graphene electrolysis electrode plate, characterized in that: include: a metal conductive substrate layer; A porous ceramic skeleton layer is located on the surface of the metal conductive substrate layer. The ceramic skeleton layer is formed into a metallurgical bonding interface by laser cladding, and the porosity is 30±5%. A chemical copper plating layer filling the pores of the ceramic skeleton layer; An electroplated nickel-ruthenium alloy catalyst layer covering the surface of the chemically plated copper layer, wherein the mass ratio of nickel to ruthenium is 9:1 and the thickness is 1-2 μm; The graphene functional layer in situ grown on the surface of the nickel-ruthenium alloy catalyst layer has 3-5 layers and ID / IG≤0.08 in the Raman spectrum.

2. The gradient composite graphene electrolysis electrode plate according to claim 1, characterized in that: The metal conductive substrate layer is one of titanium alloy, copper alloy or nickel-based high-temperature alloy, with a thickness of 2-10 mm and a surface roughness of Ra=0.8-1.2 μm.

3. The gradient composite graphene electrolysis electrode plate according to claim 1, characterized in that: The porous ceramic skeleton layer is a composite ceramic of Al2O3 and ZrO2, wherein the mass fraction of ZrO2 is 35-45%, the bending strength is ≥800MPa, and the thermal expansion coefficient is 8.5-9.5×10 -8 / ℃.

4. The gradient composite graphene electrolysis electrode plate according to claim 1, characterized in that: The crystal plane orientation of the electroplated nickel-ruthenium alloy catalyst layer is mainly (11"), accounting for ≥88%.

5. The in-situ preparation method of the gradient composite graphene electrolytic electrode plate according to any one of claims 1 to 4, characterized in that: The following steps are involved: (a) Laser cladding of ceramic powder on the surface of the metal conductive substrate to form a porous ceramic skeleton layer with a cladding power density of 300-500W / mm 2 , sintered at 1600℃ under argon protection; (b) The ceramic skeleton layer is subjected to electroless copper plating, with the plating solution containing 30±2 g / L disodium EDTA and 0.5±0.1 g / L nanodiamond particles, pH==12.8±0.2, and the reaction temperature is 60±2°C for 90 min; (c) Pulse electroplating of nickel-ruthenium alloy on the surface of the electroless copper layer, the plating solution contains RuSO4 8±1g / L, the pulse frequency is 1000±100Hz, and the duty cycle is 1:5; (d) Plating the plated substrate in a CVD device and introducing H2 for reduction at 1050°C for 2 h to form a (111) crystal plane-dominated structure on the nickel-ruthenium alloy catalyst layer; (e) A CH4 / H2 mixture (volume ratio 1:4) was pulsed in with a pulse period of 10 s (2 s on / 8 s off) to in situ grow a graphene functional layer on the surface of the nickel-ruthenium alloy catalyst layer.

6. The in-situ preparation method according to claim 5, characterized in that: In step (e), a vortex air intake method is adopted for the mesh substrate, the gas flow rate in the edge area of ​​the mesh is 1.2-1.5 times that in the center area, and the Reynolds number Re=2500±200.

7. The in-situ preparation method according to claim 5, characterized in that: In step (e), the graphene coverage is monitored in real time by a laser interferometer, and the deposition is terminated when the coverage is ≥98%.

8. The in-situ preparation method according to claim 5, characterized in that: During the reduction treatment of step (d), the H2 partial pressure is 50±5 Pa and the heating rate is ≤10°C / min.

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