A novel hybrid artificial photosynthesis system using MoS2 embedded in carbon nanofibers as electron relay and hydrogen evolution catalyst

Abstract

Inspired by photosynthesis in nature, artificial photosynthesis (AP) systems have been widely investigated in the context of energy and environmental research. Here we report a noble-metal-free AP system for visible-light-driven H-2 generation from aqueous solutions consisting of fluorescein (FL) as photosensitizer, single-layer ultrasmall MoS2 nanoplates embedded in carbon nanofibers (CNF) as electron relay and redox catalyst, and triethanolamine (TEOA) as sacrificial electron donor. This CNF-MoS2/FL system exhibits outstanding H-2 evolution performance, with an H-2 generation rate that exceeds not only both MoS2/FL (by 100%) and CNF/FL (by 1100%), but also the Pt/FL system (by 40%). The excellent photocatalytic activity of this CNF-MoS2/FL system can be ascribed to the synergistic effects of CNF and MoS2 coupling: (1) the simultaneous presence of MoS2 with its delocalized and increased Mo 4d unoccupied states and of CNF with increased graphitic characteristics enables electron transfer from FL* to MoS2 via CNF electron relay; (2) the single-layered ultrasmall MoS2 nanoplates with short effective lengths for electron transfer and high density of reactive S-edges effectively catalyze the H-2 evolution reaction (HER). The presented work successfully fabricated a highly efficient AP system for solar H-2 production from a fully aqueous solution and indicated CNF-MoS2 as a promising candidate to replace Pt for solar fuel conversion. (C) 2017 Elsevier Inc. All rights reserved.