Biomimetic mineralization synthesis of tricobalt tetraoxide/nitrogen doped carbon skeleton for enhanced capacitive deionization

Developing novel capacitive deionization (CDI) electrode materials with high salt adsorption capacity and adsorption rate is essential for desalination applications, however, encountering significant challenges. Herein, a facile and energy economical biomimetic mineralization method is proposed to construct the tricobalt tetraoxide/nitrogen doped carbon (Co3O4/NC) heterostructure. Benefiting from the mild biomimetic mineralization process, small Co3O4 nanoparticles grow uniformly on interconnected multi-branched NC skeleton. The as-obtained Co3O4/NC heterostructure exhibits a salt adsorption capacity of 44.5 mg g−1, adsorption rate of 7.9 mg g−1 min−1, and 91.3 % of capacity retention after 60 cycles at 1.2 V in 500 mg L−1 salt solution. These performances overwhelm the bare Co3O4 (24.6 mg g−1, 3.5 mg g−1 min−1, 65.7 %), indicating superior desalination performances of the Co3O4/NC heterostructure. This study gives an insight into the biomimetic mineralization method and provides one promising candidate of CDI electrode.