Mg-O-Bridged Polypyrrole/g-C3 N4 Nanocomposites as Efficient Visible-Light Catalysts for Hydrogen Evolution.

It is highly desired to improve the visible-light activity of g-C3 N4 for H2 evolution by constructing closely contacted heterojunctions with conductive polymers. Herein, a polymer nanocomposite photocatalyst with high visible-light activity is fabricated successfully by coupling nanosized polypyrrole (NPPy) particles onto g-C3 N4 nanosheets through a simple wet-chemical process, and its visible-light activity is improved further by constructing Mg-O bridges between the NPPy and g-C3 N4 . The amount-optimized bridged nanocomposite displays an approximately ninefold improvement in visible-light activity compared with g-C3 N4 . On the basis of transient-state surface photovoltage responses, photoluminescence spectra, . OH amount evaluation, and photoelectrochemical curves, it is concluded that the exceptional photoactivity can be attributed to the significantly promoted charge transfer and separation along with visible photosensitization from NPPy. Interestingly, it is confirmed that the promoted charge separation depends mainly on the excited high-level electron transfer from g-C3 N4 to NPPy by single-wavelength photocurrent action spectra. This work provides a feasible strategy for designing polymer nano-heterojunction photocatalysts with exceptional visible-light activities.