Direct-Laser-Writing of Metal Sulfide-Graphene Nanocomposite Photoelectrode toward Sensitive Photoelectrochemical Sensing

Here, a facile approach for the in situ fabrication of metal sulfide (MS)-graphene (G) nanocomposite, CdS-G and PbS-G, on indium-tin oxide (ITO) glass is demonstrated using a simple and scalable direct-laser-writing method in ambient air. Through the CO2 laser irradiation of a metal-complex-containing polyethersulfone layer on ITO glass, both the crystallization of laser-induced MS (LIMS) and the formation of laser-induced graphene (LIG) are synchronously achieved in one step, giving rise to a laser-induced MS-G nanocomposite photoelectrode, denoted as LI-MS-G@ITO. In such a laser-scribing process, polyethersulfone not only acts as the carbon source to grow LIG but also provides an in situ source of S2- to produce LIMS with the aids of carbothermic reduction of sulfur element in polyethersulfone. The obtained LI-MS-G@ITO inherits the porous network architecture of polyethersulfone-derived LIG, in which the LIMS nanocrystals uniformly decorate the multilayered graphene sheets with good dispersion, presenting a fast and stable photocurrent response with high reproducibility, which, as a proof-of-concept, further facilitates the use of a LI-CdS-G@ITO photoanode as an efficient transducer for photoelectrochemical detection of Cu2+ with high sensitivity and selectivity. This work can offer a universal and versatile protocol for the in situ and synchronous fabrication of novel MS-G nanocomposites for sensitive photoelectrochemical analysis.