Synthesis of Spherical TiO2 Particles with Disordered Rutile Surface for Photocatalytic Hydrogen Production

Na Yeon Kim,Ji Bong Joo,Jong Tae Moon,Hyeon Kyeong Lee

doi:10.3390/catal9060491

Abstract

One of the most important issues in photocatalysis research has been the development of TiO2-based photocatalysts that work efficiently under visible light conditions. Here, we report the monodispersed, spherical TiO2 particles with disordered rutile surface for use as visible-light photocatalysts. The spherical TiO2 particles with disordered surface were synthesized by sol-gel synthesis, followed by sequential calcination, and chemical reduction process using Li/Ethylenediamine (Li/EDA) solution. Variation of the calcination temperature allowed the crystalline properties of the calcined TiO2 samples, such as the ratio of anatase and rutile, to be finely controlled. The content ratios of anatase phase to rutile phase leads to different degrees of disorder of the rutile surface, which is closely related to the photocatalysis activity. Chemical reduction using the Li/EDA solution enables selective reduction of the rutile surface of the calcined TiO2, resulting in enhanced light absorption. As a result, we were able to synthesize spherical TiO2 photocatalysts having a disordered rutile surface in a mixed crystalline phase, which is beneficial during photocatalysis in terms of light absorption and charge separation. When used as photocatalysts for hydrogen production under solar light conditions, the chemically-reduced TiO2 particles with both the disordered rutile surface and mixed crystalline phase showed significantly enhanced catalytic activity.

Highlights

In modern society the energy crisis is becoming one of the biggest issues to directly impact our lives
We report the synthesis of the spherical TiO2 particle with the disordered rutile surface for photocatalytic hydrogen production
Colored TiO2 spherical particles with the disordered rutile surface were synthesized by a modified sol-gel synthesis, followed by sequential calcination at the desired temperature and chemical reduction, respectively (Figure 1a)

Summary

Introduction

In modern society the energy crisis is becoming one of the biggest issues to directly impact our lives. As people are recognizing that high concentration of carbon dioxide is closely related to global warming and climate change, hydrogen can be considered as a one of the representative alternative-energy resources to either reduce or replace the use of depletable fossil fuels. There are several strategies to produce hydrogen, such as the reforming of either fossil fuel or renewable biomass, water electrolysis, ammonia decomposition, photo-electrochemical water splitting, and photocatalytic water splitting [2,3,4,5,6,7,8]. Photocatalytic hydrogen production from water is considered as an ideal and economically-feasible method, since infinite solar energy can be used with any other type of energy resource [9].

Methods

Results

Conclusion