Dr. Khalid Umar is working as Senior Lecturer (Assistant Professor) at School of Chemical Sciences, Universiti Sains Malaysia (USM), Gelugor, Penang, Malaysia. He obtained his Ph.D. in Chemistry from Aligarh Muslim University, Aligarh, India, following which he joined Universiti Teknologi Malaysia (UTM) as a postdoctoral fellow and then as an Assistant Professor at Institute of Technology and Management Aligarh, India. Later, he joined Universiti Sains Malaysia (USM) as a postdoctoral fellow and then now working as an Assistant Professor. His areas of research interests include bio-waste assisted synthesis of graphene derivatives and metal oxide based nanophotocatalyts, degradation and intermediate study of pollutants, microbial fuel cell technology for energy generation and heavy metal remediation and utilization of lignin based nanomaterials for wastewater treatment. So far, he has published 10 book chapters and more than 60 peer-reviewed international journal papers, in addition to having served as Guest Editor of special issues of Peer Reviewed journals.