L-cysteine and urea synergistically-mediated one-pot one-step self-transformed hydrothermal synthesis of p-Ag2S/n-AgInS2 core-shell heteronanoflowers for photocatalytic MO degradation

Abstract

Delicate design and construction of Ag2S-based heterostructures with favorable interface for prominent charge separation is a grand challenge in photocatalysis. In this work, the large-scale fabrication of core-shell p-Ag2S/n-AgInS2 hetero-nanoflowers with interlaced nanosheets is demonstrated firstly by a facile one-pot one-step L-cysteine and urea co-mediated hydrothermal method. Here in-situ partial self-transformation of initially-generated monoclinic Ag2S nuclei (core) to orthorhombic AgInS2 (shell) plays a critical role in creating an atomic-level p-n nanojunction between p-Ag2S and n-AgInS2, which is validated by various techniques including XRD, SEM, HR(TEM), EDS, XPS, N2 adsorption/desorption and UV–vis DRS spectra. Benefiting from the enhanced light-response and charge-separation due to the establishment of p-n heterojunction, the photocatalytic activity of Ag2S/AgInS2 heteronanoflowers (In/Ag = 1.0, molar ratio) for MO degradation under visible light is nearly 36 and 3.4 times higher than that of pristine Ag2S and AgInS2, respectively. More Intriguingly, Ag2S/AgInS2 hetero-nanoflowers manifest exceptionally preferable photo- and chemical-stability as well as anti-photocorrosion capability, a formidable challenge encountered in many chalcogenides. This work not only highlights the great potential of Ag2S/AgInS2 hetero-nanoflowers as a less-toxic visible-light active photocatalyst, but also affords a cost-competitive and eco-friendly one-pot strategy towards in-situ fabrication of sulfide-based heterostructures with favorable interface for good performance in solar energy-related applications.