Top‐Down Fabrication of N‐GQDs Modified SnO₂ with Improved Photoelectric Characteristics

Abstract N‐graphene quantum dots (N‐GQDs) are prepared using graphite as a carbon source and ammonia as a nitrogen source by a top‐down approach, and further combined with SnO 2 to obtain SnO 2 /N‐GQDs composites by a hydrothermal method. SnO 2 /N‐GQDs composites are analyzed by morphology and structure characterization, and the composites with different N‐GQDs content are further investigated by instantaneous photocurrent response (I‐t), electrochemical impedance (EIS), linear scanning voltammetry (LSV), and Mott‐Schottky curves (MS). SnO 2 /N‐GQDs composites exhibit an obvious increment in photocurrent and a decrement in interface charge transfer impedance. When the addition of N‐GQDs is 1.5wt.%, the I‐t value of SnO 2 /N‐GQDs reaches the optimum of 3.84 × 10 −5 A cm −2 , which is 2.3 times as large as that of SnO 2 . Meantime, the carrier density of SnO 2 /N‐GQDs reaches 2.67 × 10 21 cm −3 , which is 1.5 times as high as that of SnO 2 . The improvement is attributed to the combination of SnO 2 and N‐GQDs, which promotes more charge carriers to be generated and transported under UV irradiation.