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White light phosphors have many potential applications such as solid-state lighting, full color displays, light source for plant growth, and crop improvement. However, most of these phosphors are rare-earth-based materials which are costly and would be facing the challenge of resource issue due to the extremely low abundance of these elements on earth. A new white color composite consisted of a graphitic-phase nitrogen carbon (g-C3N4) treated with nitric acid and copper-cysteamine Cu3Cl(SR)2 is reported herein. Under a single wavelength excitation at 365 nm, these two materials show a strong blue and red luminescence, respectively. It is interesting to find that the white light emission with a quantum yield of 20% can be obtained by mixing these two self-activated luminescent materials at the weight ratio of 1:1.67. Using a 365 nm near-ultraviolet chip for excitation, the composite produces a white light-emitting diode that exhibits an excellent color rendering index of 94.3. These white-emitting materials are environment friendly, easy to synthesize, and cost-effective. More importantly, this will potentially eliminate the challenge of rare earth resources. Furthermore, a single chip is used for excitation instead of a multichip, which can greatly reduce the cost of the devices. [ABSTRACT FROM AUTHOR]