# Solvothermal Synthesis of Cu2ZnSnSe4 Nanoparticles and Their Visible-Light-Driven Photocatalytic Activity

## TL;DR

Researchers made Cu2ZnSnSe4 nanoparticles using a solvothermal method and found they can efficiently break down a dye under visible light.

## Contribution

The first use of Cu2ZnSnSe4 nanoparticles as a visible-light-driven photocatalyst for dye degradation.

## Key findings

- CZTSe nanoparticles achieved 96% degradation of Congo red dye under simulated sunlight in 70 minutes.
- The photocatalytic process followed a pseudo-second-order kinetic model with a rate constant of 0.334 min−1.
- The nanoparticles showed p-type semiconducting behavior and a bandgap of 1.0 eV.

## Abstract

Cu2ZnSnSe4 (CZTSe) nanoparticles (NPs) were successfully synthesized via a solvothermal method. Their structural, compositional, morphological, optoelectronic, and electrochemical properties have been characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Field-emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), UV–vis absorption spectroscopy, and electrochemical impedance spectroscopy (EIS) techniques. Porosimetry and specific surface area in terms of the Brunauer–Emmett–Teller (BET) technique have also been studied. XRD indicates the formation of a polycrystalline kesterite CZTSe phase. Raman peaks at 173 and 190 cm−1 confirm the formation of a pure phase. TEM micrographs revealed the presence of nanoparticles with average sizes of ~90 nm. A BET surface area of 7 m2/g was determined. The CZTSe NPs showed a bandgap of 1.0 eV and a p-type semiconducting behavior. As a proof of concept, for the first time, the CZTSe NPs have been used as a visible-light-driven photocatalyst to Congo red (CR) azo dye degradation. The nanophotocatalyst material under simulated sunlight results in almost complete degradation (96%) of CR dye after 70 min, following a pseudo-second-order kinetic model (rate constant of 0.334 min−1). The prepared CZTSe was reusable and can be repeatedly used to remove CR dye from aqueous solutions.