Synergistic SERS Enhancement of Highly Sensitive and Reusable rGO-Ag-ZrO2 Thin Film Nanocomposite to Detect Synthetic Textile Dyes

The textile industry is one of the main industries that benefited from the industrial revolution. Therefore, discharging of dyes from textile, paper, plastic, and rubber industries is inevitable. This colored wastewater prevents sunlight penetration and highly affects water sources. Cationic dyes such as Rhodamine 6G (R6G) and Methylene Blue (MB) obstruct plant growth, and most of these dyes are nonbiodegradable. Thus, cationic dyes are observed to be more toxic than anionic and reactive dyes. It is a great challenge to mankind to detect and remove these toxic dyes from the aquatic ecosystem. Surface-enhanced Raman spectroscopy (SERS) is an emerging cost-effective technique for the detection of any analyte at trace levels. Further, it is very important to design a highly sensitive SERS substrate to detect toxic dyes in lower concentrations. Owing to the high cost of coinage metal SERS substrates, semiconductor-based SERS substrates have gained attention recently. Though pure semiconductors have poor SERS activity, incorporating metal and graphene derivatives can further improve their surface and optical properties and make them highly sensitive SERS active substrates. In order to address this, we attempted to synthesize a reduced graphene oxide/silver/zirconia (rGO-Ag-ZrO₂) hybrid thin film nanocomposite using the facile liquid/liquid interface method for the first time. The synergistic SERS effect of the rGO-Ag-ZrO₂ substrate is highly sensitive and efficient to detect R6G until 100 pM concentrations. The multifunctional and versatile application of the rGO-Ag-ZrO₂ substrate, such as reusability by the photodegradation method and the detection of an antibiotic drug, was also explored for the first time.