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.