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

Abstract 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 CO 2 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 S 2− 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 Cu 2+ 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.