Evans took a postdoctoral fellowship at the University of Texas at Arlington for the 1970–1971 academic year, followed by second fellowship at the University of Notre Dame in Indiana, where he worked with the organic chemist Ernest L. Eliel studying stereochemistry. Upon the completion of the fellowship, he was invited to be a research instructor at Dartmouth College in 1972, though they did not have the laboratory equipment he required to continue his research. Evans then joined the faculty of the University of North Carolina at Chapel Hill as an assistant professor of chemistry in 1974. He was the first African-American chemistry professor at the university. After 10 years at Chapel Hill, Evans became a full professor, and in 1992 was honored with a Kenan Professor chair.
Evans was a leading researcher in the field of organophosphorus chemistry, authoring more than 85 scientific articles on organosulfur and organophosphorus chemistry. His research led to a deeper understanding of the functions of organophosphate compounds and innovations in methods to produce chemical compounds for pharmaceutical drugs. Evans was inspired by William Standish Knowles, who in 1968 developed a method of asymmetric hydrogenation, which Evans used to develop alternative asymmetric synthesis methods as a way to produce single stereoisomers. Evans started experimenting with organophosphorus chemistry in 1970, developing a process using phosphorus atoms of organophosphate compounds as agents to produce specific stereoisomers. He also devised a method of asymmetric synthesis to synthesize alpha-amino phosphonic acids by adding phosphorus to sulfimides.
At the University of North Carolina Evans assembled a research team of undergraduates, graduate students, and postdoctoral fellows from around the world. In the 1980s, a Ford Foundation Fellowship allowed him to create ties between his research team and a research group at the Paul Sabatier University in France, where he spent a full sabbatical year. Later, with the help of a Fulbright Fellowship, he built ties with groups in Mexico, Poland, Germany, Greece, and Russia.
Evans championed recruiting minority applicants to UNC-Chapel Hill, while on the national front, he served on committees of the American Chemical Society, the National Institutes of Health, the National Science Foundation, and was chair of the U.S. National Committee of the International Union of Pure and Applied Chemistry. He also served on a council that advised the National Institute of General Medical Sciences.