Over the last few years, extensive research efforts have focused on development of solid-state white-light-emitting materials because of their potential for energy-efficient illumination. Common approaches to generate white light emission are either by properly mixing red, green, and blue-emitting semiconductor quantum dots or integrating them with traditional organic phosphors. However, semiconductor nanocrystals containing Cd or other heavy metals have serious toxicity as well as high costs, which considerably limits their practical applications. In recent years, compared to the quantum dots, carbon-based fluorescent nanodots including carbon dots and graphene quantum dots have emerged as promising substitutes for the present fluorescent nanomaterials because of their competitive optical performance - high photostability, non-blinking photoluminescence and versatile tunability of optical properties.

Herein we report on a facile synthesis of carbon dot species from acetylene using Ca²⁺ ion catalyst in zeolite template. The resulting product directly exhibits strong white-fluorescence in N-methyl-2-pyrrolidone (NMP) solution under a single wavelength excitation. The photoluminescence quantum yield of the white emission was determined to be 13.7 % under 340 nm excitation in NMP solution. The current synthesis method is a reliable low-cost synthetic technique, rendering potential various scientific and industrial applications.