Spherical shape-defined hollow UiO-66 metal-organic frameworks with superior incident photon scattering for enhanced photoelectrochemical H2 evolution

Herein, spherical hollow N-doped carbon-incorporated UiO-66 metal-organic frameworks (MOF, H-UiO-66) are synthesized using bio-inspired polydopamine (pDA) nanoparticles as multifunctional starting templates. The calculated band properties (ECB = -0.45 eV and EVB = 2.05 eV versus normal hydrogen electrode (NHE)) strongly reveals the visible light absorption of H-UiO-66 nanostructures thanks to the spherical shape-defined morphology as well as cavity of the hollow structure. The evaluation of photoelectrochemical (PEC) water splitting performance of H-UiO-66 photoanodes shows maximum photocurrent density as 10.95 mA/cm2 at 1.53 V versus RHE under LED illumination in which almost no response is recorded at dark. Furthermore, the improved visible-light sensitive PEC water splitting performance of H-UiO-66 photoanodes could be attributed to the main advantages of the one-pot synthesis method of hollow MOFs using multifunctional pDA as follows: i) the hollow morphology provides superior incident photon scattering and multi-reflection of photons inside the MOF cavity; ii) presence of N-doped carbon incorporated morphology facilitates the absorption of water molecules as well as the π-polar interaction between water and carbon; and iii) the reduced bang-gap led to the optical localization of light within H-UiO-66 clusters, suggesting a new generation of heterogeneous well-defined nanostructures for sustainable PEC hydrogen production.