Capacitive deionization (CDI) is considered to be an energy-efficient and cost-effective technology for ion removal from saline or waste water. However, its implementation remains challenging due to low ion adsorption capacity of the commonly used electrode materials. It is thus desirable to develop highly efficient CDI electrode materials for ion removal. Herein, graphitic porous carbon nanosheets (GPCSs) were originally prepared from straw waste via a combined activation and graphitization process. Being composed of graphitic carbon sheets with abundant pores in the framework, the obtained GPCSs had a large specific surface area and good conductivity and wettability, which can provide sufficient adsorption sites and promote efficient ion transport. The GPCS electrodes presented a higher specific capacitance, good stability and low inner resistance in electrochemical tests. Moreover, the GPCSs showed a high deionization capacity of 19.3 mg g⁻¹ at 1.2 V in a 500 mg L⁻¹ NaCl solution. Repeated adsorption–desorption experiments demonstrated the good regeneration performance of the GPCS electrodes. Furthermore, the removal efficiency towards Cd²⁺, Ni²⁺ and Cu²⁺ of the GPCS electrodes is 91.5%, 97.0% and 100% at 1.2 V in a 100 mg L⁻¹ CdCl₂ , NiCl₂ or CuCl₂ solution, respectively. This work offers a promising solution to efficient removal of ions from saline or waste water and a new route to the utilization of straw waste.

中文翻译：

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通过秸秆废料衍生的石墨多孔碳纳米片通过电容去离子有效去除金属离子

电容去离子（CDI）被认为是一种从盐水或废水中去除离子的节能且经济高效的技术。然而，由于常用电极材料的低离子吸附能力，其实施仍然具有挑战性。因此，期望开发用于离子去除的高效CDI电极材料。本文中，石墨多孔碳纳米片（GPCS）最初是通过秸秆废物通过活化和石墨化相结合的过程。所获得的GPCSs由骨架中具有大量孔的石墨碳片组成，具有较大的比表面积，良好的电导率和润湿性，可以提供足够的吸附位并促进有效的离子迁移。在电化学测试中，GPCS电极具有更高的比电容，良好的稳定性和较低的内阻。此外，GPCS在500 V L ^-1 NaCl溶液中在1.2 V下显示出19.3 mg g ^-1的高去离子容量。重复的吸附-解吸实验证明了GPCS电极具有良好的再生性能。此外，对Cd 2 ⁺，Ni ²⁺和Cu ²⁺的去除效率在100 mg L ^-1 CdCl ₂，NiCl ₂或CuCl ₂溶液中，在1.2 V电压下，GPCS电极的电极分别为91.5％，97.0％和100％。这项工作为有效去除盐水或废水中的离子提供了有希望的解决方案，并为利用秸秆废物提供了新途径。