Efficient interfacial electron transfer induced by hollow-structured ZnIn2S4 for extending hot electron lifetimes

Abstract

The photothermal effect generated by hot electrons through phonon–phonon scattering is essential to ameliorate the slow kinetics of photocatalytic hydrogen evolution. However, the hot electrons possess short lifetimes because of the fast relaxation kinetics, which induces low energy utilization efficiency. Herein, a soft template method is innovatively developed to synthesize a hollow-structured ZnIn₂S₄ with surface S vacancies, which regulates the electron accumulation/consumption ability of interfacial atoms to strengthen the interfacial interaction with NiCo₂S₄. The increase in the number of photogenerated electrons brought by multiple light scattering in hollow-structured ZnIn₂S₄ can synergize with the efficient interfacial electron transfer to accumulate the photogenerated electrons on the NiCo₂S₄ surface. Thereafter, the resulting high-concentration photogenerated electrons in NiCo₂S₄ are subsequently excited into hot electrons via the LSPR effect, which continuously supplements the hot electrons of intrinsic excitation and prolongs their lifetimes. Thus, the effectively replenished photothermal effect is responsible for greatly ameliorating the slow kinetics of photocatalytic hydrogen evolution with the apparent activation energy reduction from 49.6 kJ mol⁻¹ to 32.2 kJ mol⁻¹, and the NiCo₂S₄/ZnIn₂S₄ photocatalyst achieves a hydrogen evolution rate of 19654.0 μmol g⁻¹ h⁻¹ under visible and NIR light irradiation with an apparent quantum efficiency of 56.7% at 400 nm. This work provides a new perspective to regulate the hot electron lifetimes to realize the efficient utilization of solar energy.