Probing conducting polymers@cadmium sulfide core-shell nanorods for highly improved photocatalytic hydrogen production.

We report three types of conducting polymers (CPs), polyaniline (PANI), polypyrrole (PPY) and poly (3,4-ethylenedioxythiophene) (PEDOT) to modify the surface of the CdS nanorods to probe their photocorrosion inhibition and photocatalytic hydrogen production. Various characterizations, such as high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and density function theory (DFT) calculations have been conducted to reveal the intrinsic structure of the as-constructed CPs@CdS (@ means CPs at the surface of CdS) core-shell nanorods. The results show that the PANI and PPY shells with abundant N and C atoms can significantly enhance the binding energy of Cd and S atoms on the surface of the CdS nanorods. However, there is no obvious enhancement of binding energy at the interface of the PEDOT shell and the CdS nanorods core. Therefore, PANI@CdS and PPY@CdS possess stronger driving force than PEDOT@CdS to inject the photogenerated holes in conducting polymer shells. As a result, the polyaniline (PANI) modified PANI@CdS core-shell nanorods demonstrate the most effectively enhanced hydrogen production rate of ∼9.7 mmol h-1 g-1 and effective photocorrosion inhibition in 30 h without deactivation under visible-light irradiation. The hydrogen production performance of PPY@CdS is not effectively promoted owing to the weak transmittance of light for the PPY shell. The PEDOT shell cannot improve the hydrogen production and stability property of the CdS nanorods. This work could shed some light on conducting polymers modifying metal sulfides nanostructures that is of inconceivable significance for effective photocorrosion inhibition and highly enhanced photocatalytic activities.