Self-grown photocatalytic metal-organic frameworks on electrocatalytic NiFe layered double hydroxides as bifunctional photoelectrocatalyst for efficient overall water splitting

Photoelectrochemical (PEC) overall water splitting is an appealing carbon-neutral strategy for green hydrogen production. Herein, a compact self-grown NiFe layered double hydroxide (LDH)-metal-organic frameworks (MOF) Z-Scheme bifunctional photoelectrocatalyst is successfully constructed by the in situ partial transformation of electrocatalytic NiFe LDH to photocatalytic NiFe MOF for PEC overall water splitting. The hierarchical layered structure of NiFe LDH-MOF shows excellent bifunctional activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The incorporation of NiFe MOF significantly improves the PEC HER performance of NiFe LDH, resulting in a low overpotential of 268 mV at the current density of 100 mA cm −2 for NiFe LDH-MOF. A synergistic effect promotes the OER performance of NiFe LDH-MOF, resulting in a higher photocurrent density and lower overpotential compared to LDH and MOF individually. The compact NiFe LDH-MOF, serving as both a photocathode and a photoanode, is successfully utilized in photoelectrochemical overall alkali water splitting. It performs effectively under experimental illumination (λ ≥ 400 nm), natural sunlight, and can even be powered by a commercial dry battery. The excellent performance under solar illumination enables the self-grown LDH-MOF heterojunction material highly promising for practical applications in PEC water splitting.