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Facile and Green Approach to Synthesize Biomass-Derived Zero-/Two-Dimensional Carbon Dots/g-C3N4 Heterojunction for Efficient Photocatalytic and Photoelectrocatalytic Applications
Developing efficient photoactive materials from bio-derived resources is vital yet challenging for achieving effective water splitting performance. In this work, nano carbon dots (CDs) of zero-dimensional (0D) were synthesized from papaya peel through a simple and eco-friendly process and subsequently anchored onto the two-dimensional (2D) layered structure of graphitic carbon nitride (g-C3N4, GCN) at various composite ratios to obtain a 0D/2D nanohybrid. The optical and physicochemical properties of the resulting nanohybrids were comprehensively characterized using various analytical techniques. The catalysts were evaluated for both Rhodamine B (RhB) dye photodegradation and photoelectrochemical (PEC) water splitting applications. Among all the samples, GCN-CD-3 exhibited superior photocatalytic activity under visible-light irradiation due to its enhanced light absorption, efficient electron transfer, and effective separation of photogenerated charge carriers, achieving a rate constant of 0.0316 min−1, approximately 3.8 times higher than that of pristine GCN. Moreover, GCN-CD-3, as a photoelectrode for PEC water splitting, demonstrated an impressive photocurrent density of 3.62 mA/cm2 at a low onset potential of 0.63 V versus Ag/AgCl, surpassing the performance of other catalysts. These results demonstrate that the bio-derived nanohybrid functions as an efficient catalyst for sustainable water-splitting applications, without raising toxicity concerns.