Heteroatom doping modified hierarchical mesoporous carbon derived from ZIF-8 for capacitive deionization with enhanced salt removal rate

Abstract

Heteroatom doped carbonaceous material has attracted enormous attentions in electrochemical research community due to the replacement of some carbon atoms in the carbon skeleton result in charge redistribution and thus the modification of physiochemical properties. In this work, we proposed a facial approach to synthesize nitrogen and titanium co-doped hierarchical mesoporous carbon ((N, Ti)-HMCs) by employing ZIF-8 as procures for capacitive deionization (CDI) with enhanced performance. The as-prepared (N, Ti)-HMCs exhibits novel cubic structure, high doping content and high specific surface area of 1025.93 m2/g. The Raman spectra revealed the presence of abundant structural defects in (N, Ti)-HMCs rather than HMCs which is beneficial to promote the electrosorption. Besides, the electrochemical analysis demonstrated that (N, Ti)-HMCs owns improved specific capacitance and lower resistivity as compared to that of HMCs. Moreover, by examining the CDI performance of (N, Ti)-HMCs in a batch mode experiment, it illustrated high salt removal capacity of 13.89 mg/g at 1.2 V in a 500 mg/L NaCl solutions and outstanding adsorption rate of 3.53 mg/(g·min). Thus, (N, Ti)-HMCs should be proposed as superior electrode materials for enhanced CDI. Our work also strengthens the emphasis on heteroatom doped carbonaceous materials in CDI.