A highly active g-C3N4 isotype composite was prepared with a precursor mixture of melamine and thiourea by a one-step thermal treatment. The differences in the electronic band structure of the as-prepared isotype g-C3N4 made the band levels match with each other. This novel metal-free isotype composite was demonstrated to promote the separation of photoinduced charges, leading to a significant enhancement in the photocatalytic activity for degrading rhodamine B under visible-light irradiation. Moreover, the resultant g-C3N4 isotype composite possessed excellent stability after three recycles. Finally, the relevant mechanism for the photodegradation process was also proposed.
