VACNT Catalytic Electrode With Platinum Nanodots for Lower Pt Load
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Solution Overview
Problem
Existing catalytic electrodes for fuel cells and electrolytic cells are inefficient in utilizing platinum, with a significant fraction of platinum particles being non-catalytically active, and existing methods for improving platinum utilization are complex or result in reduced efficiency due to platinum agglomeration and blocked access to pores.
Innovation Solution
A novel catalytic electrode comprising platinum nanodots deposited onto vertically aligned carbon nanotubes (VACNT) using a one-step gas phase growth process, followed by platinum nanodot deposition with Pt(PF3)4 as a precursor, and optionally encapsulating the nanodots in a porous inorganic oxide coating to enhance homogeneity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If platinum nanoparticles are dispersed over porous carbon materials to create catalytic electrodes, then the electrode can perform fuel cell reactions, but the platinum utilization efficiency is low and the cost is high
Solution Approach 1:
The patent segments the catalyst support into vertically aligned carbon nanotubes with internal cavities, creating numerous isolated compartments that prevent platinum agglomeration and maximize the number of active sites per unit mass of platinum
Solution Approach 2:
The patent embeds platinum nanoparticles inside the hollow cavities of carbon nanotubes, creating a nested structure where the platinum is confined within the nanotube cavities, preventing migration and agglomeration while maximizing utilization
2Reliability
If vertically aligned carbon nanotubes are used to enhance gas diffusivity and platinum utilization, then catalytic performance improves, but the manufacturing process becomes complex and difficult to handle
Solution Approach 1:
The patent combines the carbon nanotube growth and platinum deposition into an integrated process where platinum is deposited during the nanotube formation, eliminating separate steps and simplifying manufacturing
Solution Approach 2:
The carbon nanotubes serve multiple functions simultaneously: they provide structural support, enable gas diffusion, drain water, and confine platinum nanoparticles, eliminating the need for separate components for each function
3Quantity of substance
If platinum particles are made small to increase surface area, then catalytic activity per mass increases, but the particles agglomerate and become less effective
Solution Approach 1:
The patent creates a specific local environment inside the carbon nanotube cavities that confines platinum particles and prevents agglomeration, maintaining small particle size and high surface area throughout the electrode structure
Solution Approach 2:
The carbon nanotube cavities automatically confine and stabilize the platinum particles through their physical structure, eliminating the need for additional stabilizing agents or complex processing steps
4Stability of the object's composition
If a compact platinum film is deposited by sputtering to cover the surface, then continuous coverage is achieved, but access to small pores is blocked and specific surface area is lost
Solution Approach 1:
The patent transitions from two-dimensional surface coating to three-dimensional confinement, placing platinum particles inside the nanotube cavities rather than coating the external surface, thereby maintaining pore accessibility while achieving complete coverage
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves improved platinum mass activity and utilization, reducing the overall platinum load and cost, with homogeneous platinum distribution and enhanced catalytic performance.
Implementation Method 1
depositing a plurality of platinum nanodots onto the outer surface of said VACNT by using a first gas phase deposition process
Implementation Method 2
depositing a plurality of platinum nanodots onto the outer surface of said VACNT by using a first gas phase deposition process using Pt(PF3)4 in the presence of an oxidizing or a reducing agent
Data Source
AI summary
A method of preparing an array of vertically aligned carbon nanotubes for use in catalytic electrodes for fuel cell or electrolytic cell, comprising: providing an array of vertically aligned carbon nanotubes obtained by a gas phase growth process in which the precursor of a carbon nanotube growth catalyst is added continuously to the feed gas; and depositing a plurality of platinum nanodots onto the outer surface of said vertically aligned carbon nanotubes by using a gas phase deposition process such as ALD. The ALD process advantageously uses a platinum source gas which is Pt(PF3)4. The nanodots can be protected by nanocaging.