A novel and porous triptycene-based microporous polymer (TMP) was synthesized through a palladium acetate-catalyzed Suzuki reaction, and then Cd0.5Zn0.5S quantum dots (CZS QDs) were homogeneously decorated onto the TMP by a facile in situ precipitation approach to fabricate a 0D/3D heterojunction for the first time. Characterizations indicate TMP with large specific surface area (809 m(2) g(-1)) not only stabilizes CZS QDs but also provides abundant photocatalytic active sites, which can facilitate the activation and adsorption of H2O molecules. The CZS QDs@TMP heterojunction possesses remarkably improved photocatalytic hydrogen evolution activity and outstanding photostability. The optimized CZS QDs@TMP-1 heterojunction exhibits highest hydrogen-producing rate of 81.33 mmol h(-1) g(-1), about 16.1 times higher than that of pristine CZS. The high photo-catalytic activity of CZS QDs@TMP is due to several positive factors, such as high surface area, construction of n-n type heterostructures, tiny size effect of CZS QDs and close contact between OD CZS QDs and 3D TMP, which will synergistically promote the visible-light response, boost the interfacial charge transfer and reduce the photocorrosion of CZS. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.