Recent Advances in TiO2-Based Photocatalysts for Reduction of CO2 to Fuels.

Thang Phan Nguyen,Sang Youn Chae,Dai-Viet N Vo,Sa-Rang Bae,Thu-Ha Le,Quang Thang Trinh,Dang Le Tri Nguyen,Quyet Van Le,Van-Huy Nguyen,Soo Young Kim

doi:10.3390/nano10020337

Abstract

Titanium dioxide (TiO2) has attracted increasing attention as a candidate for the photocatalytic reduction of carbon dioxide (CO2) to convert anthropogenic CO2 gas into fuels combined with storage of intermittent and renewable solar energy in forms of chemical bonds for closing the carbon cycle. However, pristine TiO2 possesses a large band gap (3.2 eV), fast recombination of electrons and holes, and low selectivity for the photoreduction of CO2. Recently, considerable progress has been made in the improvement of the performance of TiO2 photocatalysts for CO2 reduction. In this review, we first discuss the fundamentals of and challenges in CO2 photoreduction on TiO2-based catalysts. Next, the recently emerging progress and advances in TiO2 nanostructured and hybrid materials for overcoming the mentioned obstacles to achieve high light-harvesting capability, improved adsorption and activation of CO2, excellent photocatalytic activity, the ability to impede the recombination of electrons-holes pairs, and efficient suppression of hydrogen evolution are discussed. In addition, approaches and strategies for improvements in TiO2-based photocatalysts and their working mechanisms are thoroughly summarized and analyzed. Lastly, the current challenges and prospects of CO2 photocatalytic reactions on TiO2-based catalysts are also presented.

Highlights

Heavy dependence on fossil fuels since the past few centuries for industrialization and economic growth has depleted the sources of carbon-emitting fossil fuels and has led to record-breaking atmospheric concentrations of carbon dioxide (CO2), which is a major component of greenhouse gases, contributing to global warming and climatic changes [1,2,3]
Such systems have been considered one of the most sustainable and cost-effective approaches to exploit solar energy combined with the utilization of anthropogenic CO2 as a starting material of the carbon cycle to store energy in the form of chemical fuels [8,17,18]
The results indicate that the 3-D channel structure of zeolites in Ti-MCM-48 is beneficial for the high into CH4 and exhibited approximately 10-fold higher photocatalytic efficiency than TiO2 powder

Summary

Introduction

Heavy dependence on fossil fuels since the past few centuries for industrialization and economic growth has depleted the sources of carbon-emitting fossil fuels and has led to record-breaking atmospheric concentrations of carbon dioxide (CO2), which is a major component of greenhouse gases, contributing to global warming and climatic changes [1,2,3]. Photoreduction systems activated by solar energy are a green but intermittent power source for catalyzing the reduction of CO2 Such systems have been considered one of the most sustainable and cost-effective approaches to exploit solar energy combined with the utilization of anthropogenic CO2 as a starting material of the carbon cycle to store energy in the form of chemical fuels [8,17,18]. Parallel to water splitting technologies, an extensive line of studies on TiO2-based photocatalysts for CO2 reduction has been conducted to overcome obstacles including limited light-harvesting, charge separation hindering improved process efficiencies, inefficient selectivity of products, the inability to suppress the competing the hydrogen evolution reaction (HER), and catalytic instability [28,29,30,31]. The current challenges and directions for future progress are provided, which could offer guidelines for the future development of CO2 reduction on TiO2-based photocatalysts

Fundamentals of CO2 Photocatalytic Reduction

Modification on TiO2 Surface

Oxygen Vacancies

Cocatalysts

Metal and Metal-Oxide Cocatalysts

Conclusions and Perspective