High surface area Cu2ZnSnS4 nanosheets synthesized by microwave irradiation method: A material for detecting ammonia-ammonium ions in wastewater

Abstract

A highly sensitive and selective electrochemical sensor based on porous Cu2ZnSnS4 (CZTS) nanosheets is required for detecting ammonia-ammonium ions (NH3–NH4+). Porous CZTS nanosheets synthesized by microwave irradiation method were characterized by Raman, XRD, SEM, TEM, BET, DLS and NH3-TPD. The porous nanosheets of CZTS-30 irradiated for 30 min with a surface area of 51.3 m2 g−1 are significant material and possess many important active sites for NH3–NH4+ oxidation. The electrode was made of a glassy carbon electrode (GCE) modified by CZTS-30. It was revealed by electrochemical measurements that there were two linear ranges for NH3–NH4+. One was the high concentration ranging from 1.0 mM to 600.0 mM (R2 = 0.9989) with a sensitivity of 8.29 μA mM−1 cm−2, and the other was the low concentration between 0.1 mM and 1.0 mM (R2 = 0.9990) with a high sensitivity of 96.14 μA mM−1 cm−2. It showed a detection limit of 30 μM (S/N = 10) for the sensor in NH3–NH4+ solution mixed with 0.5 mM H2SO4 at a fixed scan rate of 20 mV s−1. This sensor also demonstrated desirable stability, reversibility and selectivity to NH3–NH4+. The CZTS/GCE is believed to become a new candidate structure for the electrochemical detection of NH3–NH4+.