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Transition metal phosphates have proved to be promising electrocatalysts for hydrogen evolution reactions (HER) of water splitting, however, further increasing their active sites and catalytic activity remains a major challenge. Herein, accordion-like Co-MOF with layered structure was synthesized. After subsequent carbonization and phosphidization, lamellar heterostructured Co/CoP nanocrystals encapsulated in a P, N co-doped C matrix (Co/CoP@PNC) was obtained. Heterojunction provides abundant active sites and improves electron transfer rate. Additionally, the effect of phosphating degree on the electrocatalytic activity was studied. In the alkaline electrolyte, the current density of the optimized Co/CoP@PNC-10 for HER reached 10 mA cm−2 at overpotential of 137 mV in 1.0 M KOH, which was superior to most of transition metal-based electrocatalysts. This work provides new guidance for the design and development of transition metal-based electrocatalysts. Co/CoP heterojunction embedded in P, N co-doped C matrix (Co/CoP@PNC) was prepared through further carbonization and phosphidization, the optimized Co/CoP@PNC exhibited excellent catalytic activity for alkaline HER. [Display omitted] • With accordion-like Co-MOF as the precursor, Co/CoP heterojunction embedded in P, N co-doped C matrix (Co/CoP@PNC) was prepared through further carbonization and phosphidization. • The phase and catalytic activity of the sample are related to the phosphating degree. • The optimized Co/CoP@PNC-10 exhibited the best performance among the series, with an overpotential of 137 mV at a current density of 10 mA cm−2 for alkaline HER. • P, N co-doped C substrate and Co/CoP heterojunction promote the overall HER performance through synergistic effect. [ABSTRACT FROM AUTHOR]

The construction of effective photogenerated charge transfer channels through interface engineering is the key to achieving the highly efficient of photocatalysts. Herein, sandwich-like ZnIn 2 S 4 /TiO 2 /Ti 3 C 2 nanosheets integrated type-II heterostructure with Schottky junction are reasonably fabricated by low temperature in-situ growth method. Benefitting from the intensive visible light absorption of ZnIn 2 S 4 , the fast electron transport of TiO 2 , the rich active sites in Ti 3 C 2 , as well as the intimate interface coupling and the matched band alignment among ternary components, enhanced hydrogen production can be achieved with ZnIn 2 S 4 /TiO 2 /Ti 3 C 2 hierarchical photocatalyst under visible light irradiation in the absence of noble metal co-catalysts. The concept of coupling type-II heterostructure with the Schottky barrier can steer the charge flow and boost the charge carrier separation and transfer across the interfacial domain, which may spark new ensemble design for efficient solar energy harvesting and conversion. [Display omitted] • The hierarchical ZnIn 2 S 4 /TiO 2 /Ti 3 C 2 photocatalysts were successfully constructed. • The enhanced hydrogen production was achieved under visible light irradiation. • The type-II heterostructure coupling with Schottky barrier can steer the charge flow. • The enhanced visible-light capture capability and more active sites promoted PHE. [ABSTRACT FROM AUTHOR]