Nadja C. Bigall

In semiconductor‐metal hybrid nanoparticles, excited charge carriers can be separated efficiently by transferring the electron to the metal, because the Fermi level is located within the bandgap of the semiconductor. Besides charge carrier separation, the catalytically active surface of the metal enables the use of these charge carriers for further reactions. Due to limited colloidal stability, the application of nanoparticles in solution is challenging. To circumvent these difficulties, the destabilization can be used to build monolithic 3D (non‐ordered) gel‐like structures with retained high surface area and an ensured diffusion within the network. Here, the resulting nanoparticle‐based hydrogels of CdSe/CdS/Pt nanoparticles show photocatalytic hydrogen production rates up to 58 (mmol(H2))/(g∙h). Due to the self‐supporting network structure, colloidal stability is unnecessary, and the applicability is improved. By simply mixing semiconductor and semiconductor–metal hybrid nanoparticles before gelation, the synthesis of the gels allows the reduction of the metal content, which further tunes the photocatalyst.