Upconversion Layer Photocatalyst for Water Splitting
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Solution Overview
Problem
Current photocatalysts for water splitting have limitations in light absorption efficiency, particularly in the visible region beyond 500 nm, necessitating additional devices or structure controls to enhance photocurrent density.
Innovation Solution
A photocatalyst comprising a semiconductor nanoparticle layer and an upconversion layer with a polymer matrix and triplet-triplet annihilation organic compounds, which absorbs long wavelengths and emits shorter wavelengths, improving light harvesting efficiency without additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a photocatalyst layer with semiconductor nanoparticles is used, then water splitting function is achieved, but light absorption efficiency in visible region (600 nm or more) is insufficient
Solution Approach 1:
An upconversion layer is introduced as an intermediary between the light source and the photocatalyst layer. This layer contains organic compounds that absorb low-energy photons (600 nm or more) and convert them to higher energy photons through upconversion, which are then absorbed by the photocatalyst layer to generate electron-hole pairs, thereby improving both light absorption efficiency and photocurrent density in the visible region
Solution Approach 2:
The invention creates a composite structure combining the photocatalyst layer (with semiconductor nanoparticles like BiVO4) and the upconversion layer (with organic compounds). This composite material system enables the photocatalyst to utilize both direct sunlight and upconverted light from the organic layer, significantly enhancing visible light absorption and photocurrent generation
2Use of energy by moving object
If doping or nanostructure control is applied to improve light harvesting efficiency, then absorption in existing wavelength region is improved, but additional devices or structure controls are required
Solution Approach 1:
The upconversion layer acts as a mediator that simplifies the system by converting unavailable light wavelengths into usable ones, eliminating the need for complex additional devices or structure controls. The organic compounds in the upconversion layer perform the wavelength conversion function that would otherwise require sophisticated optical systems
Solution Approach 2:
The invention changes the optical parameters of the system by introducing materials with specific upconversion properties. The organic compounds are selected and configured to absorb specific wavelengths (600 nm or more) and emit at wavelengths suitable for photocatalyst absorption, thereby optimizing light harvesting without complex structural modifications
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 solution enhances photocurrent density by 15% or more and hydrogen production, effectively utilizing visible light for water splitting without additional devices or structure controls.
Implementation Method 1
an upconversion layer positioned at the below of the photocatalyst layer and including a polymer matrix and a triplet-triplet annihilation organic compound
Implementation Method 2
a polymer matrix and a triplet-triplet annihilation organic compound
Implementation Method 3
a photocatalyst that absorbs solar light to excite electrons from the valence band to the conduction band
Implementation Method 4
A photocatalyst means a material that promotes chemical reactions caused by various types of light including solar light
Data Source
AI summary
Provided are a photocatalyst, a method for preparing the same, and a water splitting apparatus including the same. Without using an additional device, a photoelectrode with improved current density may be obtained through visible light absorption using the upconversion.