Fluorescent carbon quantum dots, capacitance and catalysis active porous carbon microspheres from beer

Abstract

Fluorescent nitrogen containing carbon quantum dots (NCQDs) and porous carbon microspheres (PCMs) were simultaneously synthesized by a facile hydrothermal method using beer as precursor. The afforded NCQDs in supernatant exhibited strong blue fluorescence in aqueous solution and dry state under UV light excitation, showing the huge potential as fluorescent dye. The PCMs in sediment showed great potential in supercapacitor electrode and catalyst for certain reaction. After ZnCl₂ activation at 900 °C, the obtained highly porous a-PCM₉₀₀ (denoted according to activation temperature) offered a high specific capacitance of 273.2 F g⁻¹ at 1 A g⁻¹, excellent rate capability and cycling stability when employed as supercapacitor electrode. Moreover, a-PCM₉₀₀ could also serve as efficient non-noble metal catalyst for reduction conversion of 4-nitrophenol to 4-aminophenol by NaBH₄ with high activity and well reusability.