Carbon-covered Fe-pillared bentonite electrode boosting capacitive deionization

Capacitive deionization (CDI), as an energy-efficient desalination technique, has attracted worldwide attention. Bentonite , a natural clay with 2-dimensional structure, is much popular for water treatment because of its high adsorption capacity , low cost and environmental benign properties. However, the poor conductivity and narrow interlamellar spacing limit its electrochemical application. In this work, a carbon-covered Fe-pillared bentonite (PILB@C) was fabricated as a new type of electrode materials for CDI. Through Fe-pillaring in bentonite, the interlayer spacing enlarged, accompanied with enhanced specific surface areas and abundant mesopores . The further carbon coating endowed the bentonite with good conductivity and facilitating ion-transportation. The dual-regulated composites possessed the negatively charged surface feature, favorable for inverted capacitive deionization (i-CDI) with improved deionization performance. Under the optimal carbon loading, the PILB@C electrode delivered a superior desalination capacity (16.23 mg g −1 , in 10 mM NaCl). Because of the intrinsic structural stability of bentonite, the desalination system exhibited the excellent cycling stability (90 % capacity retention over 50 cycles). When applied for industrial and domestic water purification , the PILB@C electrode realized salinity reduction and de-mineralization. This natural bentonite is nontoxic and cheap, rendering it highly promising as an electrode material candidate for future water treatment.