Copper tungstate deposited reduced graphene oxide nanocomposite for highly efficient capacitive deionization

Copper tungstate (CuWO4) decorated 2-dimensional reduced graphene oxide (CWO/rGO) has been successfully fabricated via solvothermal synthesis at 180 degrees C for 12 h, and then utilized for capacitive deionization (CDI) applications. After deposition of 20 - 40 nm spherical CuWO4 nanoparticles onto few-layered rGO nanosheets, the specific surface area can be up to 338 m2 g-1 with abundant 2 - 10 nm mesopores, which can accelerate the ion transport to augment the electrochemical performance. The CWO/rGO nanocomposite also exhibits high specific capacitances of 380 and 327 F g-1 at 0.5 A g-1 and 5 mV s-1, respectively. Furthermore, the specific electrosorption capacity (SEC) of CWO/rGO is highly dependent on environmental parameters including NaCl concentration, flow rate, applied potential, and solution temperature. An excellent SEC of 54.1 mg g-1 is achieved when 1000 mg L-1 NaCl was used at 1.4 V. Both Faradaic and electric double layer capacitances contribute the electrosorption capacity to the CDI performance of CWO/rGO where CuWO4 provides electroactive sites and rGO enhances the electric conductivity as well as offers mesoporous channels for electrosorption of ions. Meanwhile, the high charge efficiency of 95 %, lower energy consumption of 0.32 kWh m-3, and longterm stability of 50 charging-discharging cycles make the CWO/rGO a potential material for brackish water desalination, which can elucidate on the development of highly efficient desalination technologies.

Automated summary

Copper tungstate (CuWO4) decorated 2-dimensional reduced graphene oxide (CWO/rGO) nanocomposite with large specific surface area and abundant mesopores was synthesized and used for capacitive deionization (CDI). The CuWO4 provides electroactive sites and the rGO enhances electric conductivity and offers mesoporous channels for electrosorption of ions. The CWO/rGO exhibits high specific capacitances, specific electrosorption capacity, charge efficiency, low energy consumption, and long-term stability, making it a potential material for brackish water desalination.