Spontaneous formation of gold nanoparticles on MoS₂ nanosheets and its impact on solution-processed optoelectronic...

Understanding size-dependent properties of 2D materials is crucial for their optimized performance when incorporated through solution routes. In this work, the chemical nature of MoS₂ as a function of nanosheet size is investigated through the spontaneous reduction of chloroauric acid. Microscopy studies suggest higher gold nanoparticle decoration density in smaller nanosheet sizes, resulting from higher extent of reduction. Further corroboration through surface-enhanced Raman scattering using the gold-decorated MoS₂ nanosheets as substrates exhibited an enhancement factor of 1.55 × 10⁶ for smaller nanosheets which is 7-fold higher as compared to larger nanosheets. These plasmonic-semiconductor hybrids are utilized for photodetection, where decoration is found to impact the photoresponse of smaller nanosheets the most, and is optimized to achieve responsivity of 367.5 mAW^-1 and response times of ∼17 ms. The simplistic modification via solution routes and its impact on optoelectronic properties provides an enabling platform for 2D materials-based applications.