Chapter 8. Composites of Carbon Nanodots for Hydrogen Energy Generation

Abstract

This chapter discusses the synthesis of carbon nanocomposites based on zero-dimensional (0D) carbon nanodots with other carbonaceous nanostructures. We include three types of carbon nanodots in our study. These are carbon dots (CDs), graphene quantum dots (GQD), and carbon nitride quantum dots (CNQDs). Our emphasis is on the applications of these materials in solar-powered hydrogen (H2) evolution. Electronic structure calculations and different spectroscopy results demonstrate that they have a suitable conduction band (CB) and valence band (VB) position for H2 generation under solar light. Carbon nanodots serve as an excellent photosensitizer and electron relay center. Thus, in conjugation with other carbonaceous nanostructures, the nanodots can extend the carrier lifetime. Furthermore, carbon quantum dots show infrared responsive unconverted photoluminescence. Therefore, in a carbon composite nanostructure, carbon nanodots extend the photon absorption to the near infrared (NIR) region. This chapter starts with the fabrication of various carbon nanodots and their carbon-based hybrid nanocomposites. We provide an elaborate review of functional group present on the interface engineering and electronic structure tuning for simultaneous carrier separation and easy electron transport. Finally, for each composite nanostructure, we show the H2 evolution possibilities under simulated solar light.