Chinese scientists have developed a metal-free catalyst that can purify pathogen-rich water in half an hour. 

The study published in the latest version of journal Chem described the method that could produce drinking water in 30 minutes with a disinfection efficiency over 99.9999 percent under visible light. 

To disinfect water with sunlight and with metal is cost-effective but leads to second pollution. The metal-free catalysts, however, tend to have lower efficiency, according to the study. 

Researchers from Yangzhou University and the Institute of Process Engineering (IPE) of the Chinese Academy of Sciences developed a material based on graphitic carbon nitride. 

They used wet-chemical method to introduce certain chemical groups at the edges of graphitic carbon nitride, significantly improving its ability to disinfect. 

"Its first-order disinfection rate was five times higher than that of previously reported best metal-free photocatalysts with only one tenth catalyst consumption," said the paper's co-author Wang Chengyin from Yangzhou University.