An energy band compactable B-rGO/PbTiO3 p–n junction: a highly dynamic and durable photocatalyst for enhanced photocatalytic H2 evolution

Reduced graphene oxide (rGO) intentionally doped with boron atoms is a promising tactic to extract bandgap energy and p-type semiconducting behavior from graphene-based materials. Moreover, the integration of p-type boron-doped rGO with an n-type material through a heterojunction interface exhibits complementary properties to restrict the fast recombination of charge carriers and enhance the photoreaction towards energy applications. Herein, we have prepared boron-doped rGO/PbTiO3 p-n heterojunctions via a hydrothermal method. The successful formation of an excellent p-n heterojunction was demonstrated by TEM, XPS and Raman analysis. The constructed boron-doped rGO/PbTiO3 p-n heterojunctions exhibit dramatic increases in photoelectrochemical and photocatalytic performance due to the presence of a space charge region at the interface of the two materials. The scenario also revealed the double-edge sword functions of B-rGO: the material itself (i) acts as a visible light active photocatalyst with a band gap energy of 2.7 eV and (ii) participates in enhanced charge transfer via the band edge alignment between B-rGO and PbTiO3, as elucidated from photoluminescence and electrochemical impedance studies. Furthermore, the optimal 2B-rGO/PT p-n heterojunction possesses outstanding repeatability and exhibited the highest rate of hydrogen evolution, i.e. 293.79 μmol h-1 under visible light irradiation. The results for these materials may provide advanced insight into the design of next-generation high-efficiency black graphene-based heterojunctions.