Gradient synthesis of carbon quantum dots and activated carbon from pulp black liquor for photocatalytic hydrogen evolution and supercapacitor

Advanced Composites and Hybrid Materials 2023

Gradient synthesis of carbon quantum dots and activated carbon from pulp black liquor for photocatalytic hydrogen evolution and Supercapacitor

Xinrui Chen   · Siyu Zhao · Xiheng Kang   · Caiyu He   · Peitao Zhao   · Xianzhi Meng   · Arthur J. Ragauskas · Jingdong Pang · Xueping Song

摘要：Black liquor (BL) is a by-product of the chemical pulping industry and is mainly used as a low-value fuel; however, its potential to produce high-value products has not been fully exploited. In this study, a green and simple strategy is reported for the gradient production of Na+-functionalized carbon quantum dots (Na+-CQDs) for the first time, N and S co-doped CQDs (N/S-CQDs), and N and S co-doped KOH-activated carbon (N/S-KAC) from BL by dialysis, hydrothermal carbonization and activation-carbonization, respectively. Due to the good electron trapping ability, photoluminescence and promising up-conversion luminescence of CQDs, the hydrogen evolution efficiency of Na+-CQDs/TiO2 and N/S-CQDs/TiO2 photocatalysts was improved by 2.45 and 1.46 times, respectively, compared with pure TiO2. N/S-KAC with a high specific surface area of 2294 m2 g−1 provides an excellent specific capacitance of 253 F g−1 at 0.5 A g−1 and a promising energy density of 26.92 Wh kg−1 under a power density of 566 W kg−1 for the fabricated symmetrical supercapacitor. Moreover, the electrode material has good cycling stability with a capacitance retention of ~93.91% after 5000 cycles. This pathway provides a versatile and scalable approach for the construction and co-production of nanostructured materials, photocatalysts and energy storage devices.

DOI：https://doi.org/10.1007/s42114-023-00714-4