Hierarchically porous S-scheme CdS/UiO-66 photocatalyst for efficient 4-nitroaniline reduction

Unveiling the pore-size performance of metal organic frameworks (MOFs) is imperative for controllable design of sophisticated catalysts. Herein, UiO-66 with distinct macropores and mesopores were intentionally created and served as substrates to create advanced CdS/UiO-66 catalysts. The pore size impacted the spatial distribution of CdS nanoparticles (NPs): CdS tended to deposit on the external surface of mesoporous UiO-66, but spontaneously penetrated into the large cavity of macroporous UiO-66 nanocage. Normalized to unit amount of CdS, the photocatalytic reaction constant of macroporous CdS/UiO-66 over 4-nitroaniline reduction was ∼3 folds of that of mesoporous counterpart, and outperformed many other reported state-of-art CdS-based catalysts. A confinement effect of CdS NPs within UiO-66 cage could respond for its high activity, which could shorten the electron-transport distance of NPs-MOFs-reactant, and protect the active CdS NPs from photocorrosion. The finding here provides a straightforward paradigm and mechanism to rationally fabricate advance NPs/MOFs for diverse applications.