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Precise control over doping of photocatalysts is required to modulate their photocatalytic activity in visible light-driven reactions. Here, a single precursor-employing bottom-up approach is developed to produce different heteroatom-doped graphene quantum dots (GQDs) with unique photocatalytic activities. The solvothermal reaction of a norepinephrine precursor with redox active and condensable moieties effectively produces both nitrogen/sulfur codoped GQDs (NS-GQDs) and nitrogen-doped GQDs (N-GQDs) by simply varying solvents (from dimethyl sulfoxide to water) under microwave irradiation. As-prepared NS-GQDs and N-GQDs show similar lateral sizes (3-4 nm) and heights (1-2 nm), but they include different dopant types and doping constitution and content, which lead to changes in photocatalytic activity in aerobic oxidative coupling reactions of various amines. NS-GQDs exhibit much higher photocatalytic activity in reactions under visible light than N-GQDs and oxygen-doped GQDs (O-GQDs). The mechanism responsible for the outstanding photocatalytic activity of NS-GQDs in visible light-driven oxidative coupling reactions of amines is also fully investigated. [ABSTRACT FROM AUTHOR]