Conductive MoS₂ Quantum Dot/Polyaniline Aerogel for Enhanced Electrocatalytic Hydrogen Evolution and Photoresponse Properties

The low conductivity and poor active sites of MoS₂ sheet present a huge barrier for it is exploitation of catalytic applications in the hydrogen evolution reaction (HER). To alleviate this difficulty, we have synthesized MoS₂ quantum dots (QDs) having greater quantity of catalytic edge sites by breaking up the bulk MoS₂ sheet using the solvent exfoliation technique. The synthesized MoS₂ QDs are embedded into polyaniline (PANI)–N,N′-dibenzoyl-l-cystine (DBC) hydrogel matrix by in situ polymerization of aniline where DBC acts as a gelator, dopant, and cross-linker. The hybrid conducting aerogels (DBC-MoS₂-PANI) thus produced act as an efficient electrocatalyst showing lower HER overpotential in comparison to MoS₂ QDs. It exhibits an optimum overpotential value of 196 mV at 10 mA cm^–2, a favorable Tafel slope of 58 mV/dec, and an excellent cyclic stability. Also, DBC-MoS₂-PANI aerogel is used in photoresponding devices. The DBC-MoS₂-PANI hybrid aerogel exhibits a better photoresponse compared to the DBC-PANI aerogel and MoS₂ QDs upon white light illumination of 1 sun. The hybrid aerogel exhibits a maximum enhancement of photocurrent to the value of 3.95 mA at 2 V bias, and the time-dependent photoillumination shows much faster rise and decay of photocurrent compared to those of DBC-PANI aerogel and MoS₂ QDs.