Multilevel hollow hierarchical heterostructure with DB-IEF and space-confined effect for enhanced bifunctional PHE/HER activity

In photocatalytic/electrocatalytic water splitting processes, charge carriers are the main limiting factor of enhanced yield, and the enhanced charge dynamics related to the generation, transport, separation and utilization of charge is considered to be an effective measure to solve the above problems. In this study, multilevel hollow hierarchical In2S3/ZnIn2S4/CdIn2S4 (IS/ZIS/CIS) with heterogeneous spatial confinement was successfully prepared by one-step solvothermal method. The strong dual cascade built-interface electric field (DB-IEF) of the IS, ZIS and CIS contact interfaces (ISIZIS and ZISICIS) is beneficial for migrating electrons and tailoring the electronic structures of the active centers near the ISIZIS and ZISICIS interfaces. The as-constructed IS/ZIS/CIS shows outstanding bifunctional photocatalytic/electrocatalytic water splitting activity, which can not only offer high electrocatalytic activities toward HER with a low overpotential of 61 mV (vs. RHE) at 10 mA & sdot;cm- 2, with low Tafel slopes of 68 mV & sdot;dec-1 in alkaline solutions, but also achieve a higher H2 evolution rate of 4.42 mmol g- 1 & sdot;h- 1. Meanwhile, the Brunauer-Emmett-Teller surface area (BET) and pore size distribution revealed that multilevel hollow hierarchical IS/ZIS/CIS heterostructure owns hierarchical microporous/mesoporous structure, which facilitates light absorption and multiple reflections. The efficiently interfacial charge transfer and bifunctional catalytic activity could be attributed to the established DB-IEF and spatial confinement effect could drive carrier transmission, realize effective charge separation, utilization, and prolong lifetimes. This work can provide a new synthesis strategy of establishing the hierarchical heterostructure catalysts for boosting charge transfer and photocatalytic/electrocatalytic water splitting.