Pristine and cobalt doped copper sulfide microsphere particles for seawater splitting

In this work, copper sulfide particles are synthesized with different Co doping concen-trations such as 0, 1 and 5% at 80 degrees C by optimizing synthesis times from 1 to 3 h. Copper sulfide particles possess two structural phases of covellite CuS and digenite Cu9S5. The increase in synthesis time from 1 to 3 h increases the Cu9S5 phase growth and changes the morphology from flower to microsphere. The CuS synthesized with 0, 1 and 5% Co dopant concentrations demonstrate flower consisting of agglomerated nanosheets, microsphere and flower like microsphere. The elemental investigation substantiates Co ions presence in CuS microspheres. The A1g (LO) mode intensity is decreased with increase in Co dopant concentration confirming Co incorporation into CuS microsphere. The CuS synthesized with 0, 1, 5% Co dopants exhibit 322 mV, 305 mV and 289 mV to attain 100 mA/cm2 in 1 M KOH seawater. The CuS synthesized with 5% Co dopant demonstrates higher double layer capacitance (Cdl) of 173.9 mFcm-2 and lower charge transfer resistance (Rct) of 6.07 U with 78.84% retention after 10 h continuous stability than that of the other pristine (118.3 mFcm-2, 13.72 U) and 1% Co doped CuS microsphere (165.7 mFcm-2, 8.55 U) indicating more surface active site and rapid charge carrier transport, respectively.(c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, CuS microspheres were successfully synthesized with different synthesis times and Co doping concentrations. The Co doping significantly affected the morphology and electrochemical performance of CuS microspheres, with 5% Co-doped CuS demonstrating enhanced double layer capacitance and charge transfer properties.