Graphene Quantum Dots Improved "Caterpillar"-like TiO2 for Highly Efficient Photocatalytic Hydrogen Production.

Jing Ma,Lihua Chu,Changxu Sun,Meicheng Li,Ze Li,Yanjiao Guo,Hao Yan

doi:10.3390/ma14185354

Abstract

Photocatalytic water splitting for hydrogen production via heterojunction provides a convenient approach to solve the world crises of energy supply. Herein, graphene quantum dots modified TiO2 hybrids (TiO2-GQDs) with a “caterpillar”-like structure exhibit stronger light absorption in the visible region and an enhanced hydrogen production capacity of about 3.5-fold compared to the pristine TiO2 caterpillar. These results inferred that the addition of GQDs drastically promotes the interfacial electron transfer from GQDs to TiO2 through C–O–Ti bonds via the bonding between oxygen vacancy sites in TiO2 and in-plane oxygen functional groups in GQDs. Using a “caterpillar”-like structure are expected to provide a new platform for the development of highly efficient solar-driven water splitting systems based on nanocomposite photocatalyst.

Highlights

Quantum Dots Improved “Caterpillar”Global energy inequality, climate change, and consumption of fossil fuels have prompted researchers to turn their attention toward renewable energy [1]
The size and morphologies of the pristine TiO2 caterpillar, graphene quantum dots (GQDs) and their hybrids were characterized by scanning electron microscopy (SEM), TEM and high resolution TEM (HRTEM)
It is proposed that ultrasound can induce the formation of oxygen vacancies in TiO2 caterpillars, and the rearrangement of in-plane epoxy functional groups in GQDs, such that they can form hybrids through the possible C–O–Ti bonds

Summary

Introduction

Quantum Dots Improved “Caterpillar”Global energy inequality, climate change, and consumption of fossil fuels have prompted researchers to turn their attention toward renewable energy [1]. Since Fujishima and Honda reported the photoelectrochemical hydrogen evolution process from water in 1972, efficient photoconversion of water to hydrogen has been a long-term goal in the field of photocatalysis [4,5]. Titanium dioxide (TiO2 ) is considered one of the most promising photocatalysts due to its relatively low price, environmental friendliness, superior photocatalytic performance, and long-term stability [6,7]. Due to the wide band gap energy of TiO2 (anatase 3.2 eV), its light absorption range is mainly limited to the ultraviolet (UV) region, and the separation efficiency of photogenerated electron-hole pairs is low, which hinders the development of TiO2 in the field of photocatalysis [9]. In order to improve the photocatalytic performance, heterogeneous catalysts that combine semiconductor quantum dots (QDs) with TiO2 have been proposed, such as CdS, CdSe, PbS, etc. [10,11]

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Conclusion