Graphene-carbon 2D heterostructures with hierarchically-porous P,N-doped layered architecture for capacitive deionization.

Jingru Guo,Liping Wang,Jonathan P Hill,Yunqing Kang,Jingjing Dang,Weisheng Guan,Yusuke Yamauchi,Xingtao Xu,Yuliang Li

doi:10.1039/d1sc00915j

Abstract

Exploring a new-family of carbon-based desalinators to optimize their performances beyond the current commercial benchmark is of significance for the development of practically useful capacitive deionization (CDI) materials. Here, we have fabricated a hierarchically porous N,P-doped carbon–graphene 2D heterostructure (denoted NPC/rGO) by using metal–organic framework (MOF)-nanoparticle-driven assembly on graphene oxide (GO) nanosheets followed by stepwise pyrolysis and phosphorization procedures. The resulting NPC/rGO-based CDI desalinator exhibits ultrahigh deionization performance with a salt adsorption capacity of 39.34 mg g−1 in a 1000 mg L−1 NaCl solution at 1.2 V over 30 min with good cycling stability over 50 cycles. The excellent performance is attributed to the high specific surface area, high conductivity, favorable meso-/microporous structure together with nitrogen and phosphorus heteroatom co-doping, all of which are beneficial for the accommodation of ions and charge transport during the CDI process. More importantly, NPC/rGO exhibits a state-of-the-art CDI performance compared to the commercial benchmark and most of the previously reported carbon materials, highlighting the significance of the MOF nanoparticle-driven assembly strategy and graphene–carbon 2D heterostructures for CDI applications.

Highlights

With an increasing world population, worsening environment, and climate and energy crises,[1,2,3,4] the economical supply of clean, potable water is rapidly becoming a critical issue for human subsistence
The excellent performance is attributed to the high specific surface area, high conductivity, favorable meso-/microporous structure together with nitrogen and phosphorus heteroatom co-doping, all of which are beneficial for the accommodation of ions and charge transport during the capacitive deionization (CDI) process
Multiheteroatom-doped carbon materials ought to have higher values for salt adsorption capacity (SAC) than carbons doped with single types of heteroatom, due to both the individual properties contributed by each doped heteroatom and to any synergistic effects occurring between the heteroatom dopants present.[27,28,29]

Summary

Introduction

With an increasing world population, worsening environment, and climate and energy crises,[1,2,3,4] the economical supply of clean, potable water is rapidly becoming a critical issue for human subsistence.

Results

Conclusion