%0 Journal Article
%T Selective Capacitive Removal of Pb2+ from Wastewater over Biochar Electrodes by Zinc Regulation.
%A Wu Y
%A Feng H
%A Tang J
%A Yang Z
%A Lan C
%A Guo Y
%A Tang L
%J Small
%V 20
%N 28
%D 2024 Jul 13
%M 38348946
%F 15.153
%R 10.1002/smll.202311401
%X Biochar materials have shown great potential for broad catalytic application. However, using these materials in the capacitive deionization technology (CDI) system for heavy metal removal still faces a significant challenge due to their low specific capacity and removal capability. Here, a comprehensive regulation on the interfacial/bulk electrochemistry of biochar by Zn doping is reported, which suggests a high renewable capacity (20 mg g-1) and outstanding selective capacitive removal ability (SCR) of Pb2+ from leachate. The SCR efficiency of Pb2+ is as high as 99% compared to K+ (8%), Na+ (13%), and Cd2+ (37%). This work proves that the doped Zn on the biochar can combine with OH- generated by water splitting to form M─OH bonds, which is beneficial for improving the specific capacity. Significantly, the relationship between double-layer capacitance and pseudo-capacitance can also be optimized by regulating the content of Zn, leading to different removal abilities of heavy metals. Therefore, this work offers insights into charge-storage kinetics, which provide valuable guidelines for designing and optimizing the biochar electrode for broader environmental applications.