Well-defined core/shell pDA@Ni-MOF heterostructures with photostable polydopamine as electron-transfer-template for efficient photoelectrochemical H2 evolution

Here, novel core/shell polydopamine@Ni-MOF (pDA@Ni-MOF) heterogeneous nanostructures are synthesized via a simple one-pot nucleation-growth technique. This rational core/shell design method provide a uniform Ni-MOF shell thickness (shell: ∼ 10 nm) as well as homogeneous wrapping of pDA templates with quite narrow size distributions. The obtained band properties of bare pDA ( E CB = −0.35 eV and E VB = 2.95 eV vs normal hydrogen electrode (NHE)) and bare Ni-MOF ( E CB = −0.49 eV and E VB = 2.85 eV vs NHE) clearly revealed charge separation is occurred on pDA by absorbing light due to π-π∗ transition, and photogenerated electrons on conduction band (CB) of pDA was migrated to CB of Ni-MOF. Specifically, the photoelectrochemical (PEC) water performance of pDA@Ni-MOF photoanodes with highest current density is recorded as 8.61 mA/cm 2 at 0.77 V vs. RHE under visible LED irradiation, which is significantly higher than bare pDA (0.008 V vs. RHE) and bare Ni-MOF (0.011 V vs. RHE) at the same conditions. Note that, the higher photon absorption properties of pDA in core together with high interaction valence bond between two semiconductors could generate electron rich state giving rise to faster electron transfer kinetics as next generation of MOF based hybrid materials with regular morphologies. • One-pot nucleation-growth me-thod is utilized to produce core/shell pDA@Ni-MOF. • Charge separation is done on pDA by absorbing light due to π-π∗ transition. • Photogenerated electrons on pDA is migrated to Ni-MOF. • Highest current density is recorded as 8.61 mA/cm 2 at 0.77 V vs. RHE. • The charge transfer mechanism is verified by XPS.