Reduced Titania Photocatalyst for Visible Light Hydrogen Production

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Solution Overview

Problem

Conventional titania photocatalysts are limited in their ability to react in the visible light range, as they primarily respond to ultraviolet light, and doping methods often introduce defects that reduce performance.

Innovation Solution

A method involving the reduction of metal oxides, specifically titania, by mixing with metal hydrides and subsequent heat-treatment, which regulates the reduction level to enhance photocatalytic efficiency in the visible light range, including the use of magnesium hydride to control the bandgap and oxygen vacancies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If anatase titania is used as a photocatalyst, then oxidation energy and photocatalytic activity are improved, but response to visible light is insufficient

Engineering Contradiction:

Improveoxidation energyVSAvoidvisible light response

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The patent applies parameter changes by controlling the reduction level of titania through regulated heat treatment. This modifies the chemical composition and electronic structure of the material, creating oxygen vacancies and reducing Ti4+ to Ti3+, which narrows the bandgap and enables visible light absorption while preserving the anatase crystal structure's high oxidation energy

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure by combining reduced titania (with oxygen vacancies and Ti3+ sites) with the anatase crystal structure. This composite approach integrates the high oxidation energy of anatase with the visible light absorption capability of reduced titania, achieving both properties simultaneously

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If metal ions are doped to extend light absorption to visible range, then visible light response is improved, but defects and charge imbalance are generated

Engineering Contradiction:

Improvevisible light responseVSAvoidcharge balance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent takes out the problematic metal ion doping approach and replaces it with a reduction method using hydrogen or carbon-containing gases. This extraction of the harmful element (metal ions) eliminates the associated defects and charge imbalance while achieving the desired visible light absorption through oxygen vacancy creation and Ti3+ formation

Inventive Principle:

Principle #2Taking out (Extraction)

3Use of energy by moving object

If reduced titania is used to enhance visible light absorption, then visible light absorbing capacity is improved, but water splitting efficiency is lower than expected

Engineering Contradiction:

Improvevisible light absorbing capacityVSAvoidwater splitting efficiency

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent optimizes the reduction level by controlling heat treatment parameters (temperature, time, atmosphere composition) to achieve the optimal concentration of oxygen vacancies and Ti3+ sites. This precise parameter control ensures sufficient visible light absorption while maintaining enough Ti4+ sites for effective water splitting and charge balance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs feedback control by monitoring the reduction level and adjusting heat treatment conditions to achieve the optimal balance between visible light absorption and water splitting efficiency. The process is optimized based on observed performance to maintain both properties at acceptable levels

Inventive Principle:

Principle #23Feedback

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 produces a titania photocatalyst with improved visible light absorption and hydrogen generation efficiency, achieving solar hydrogen production rates of 1-4% and stability, making it suitable for cost-effective hydrogen production from water using sunlight.

Implementation Method 1

a method of reducing a metal oxide comprising the following steps: preparing a mixture by mixing a metal oxide and a metal hydride (step 1); and reducing the mixture above by heat-treatment (step 2)

Methodology Applied

Scientific EffectReduction: Reduction

Implementation Method 2

reducing the mixture above by heat-treatment (step 2)

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Implementation Method 3

heat-treating the mixture in an atmosphere in which hydrogen (H2) is supplied (step 2)

Methodology Applied

Scientific EffectReduction: Reduction

Data Source

PatentUS11260368B2Method for reducing metal oxide and method for producing photocatalyst using same

Publication Date: 2022.03.01 DAEGU GYEONGBUK INSTITUTE OF SCIENCE AND TECHNOLOGY

AI summary

The present invention relates to a method of reducing a metal oxide comprising the steps of preparing a mixture by mixing a metal oxide and a metal hydride (step 1) and reducing the mixture by heat treatment (step 2) and a method of producing a photocatalyst using the same, and The method of reducing a metal oxide of the present invention can easily reduce such metal oxides as TiO2, ZrO2, V2O3, and Fe2O3.