Display omitted •The PtO@Ti3C2/TiO2 composite is obtained via Ti3C2 MXene in-situ conversion and following PtO nanodots photo-deposition.•The Ti3C2 MXene and PtO nanodots effectively separate the photogenerated electrons and holes.•The PtO nanodots also largely suppress the hydrogen back reaction.•The PtO@Ti3C2/TiO2 composite demonstrates remarkable photocatalytic H2 production efficiency. Increasing the separation efficiency of photogenerated carriers and preventing the hydrogen back oxidation are two key challenges in photocatalytic hydrogen production. Herein, we report a promising PtO@Ti3C2/TiO2 photocatalyst to overcome these two challenges by in-situ growing TiO2 nanosheets on Ti3C2 MXene (to improve charge separation) and depositing PtO nanodots (to diminish hydrogen back reaction) for enhanced photocatalytic hydrogen production. Within this design principle, the photogenerated electrons and holes in the PtO@Ti3C2/TiO2 composites flow in opposite direction into PtO and Ti3C2 respectively, resulting in effective separation of the photogenerated electrons and holes. Beyond, the higher oxidation state of PtO nanodots also largely suppresses the undesirable hydrogen back oxidation reaction. Thereby the PtO@Ti3C2/TiO2 composite demonstrates remarkable hydrogen production efficiency. Our work here indicates that rational design of dual co-catalysts could not only promote the separation of photogenerated carriers for enhanced hydrogen production, but also inhibit the reverse reaction of hydrogen production.