Carbon nanotube-decorated hierarchical porous nickel/carbon hybrid derived from nickel-based metal-organic framework for enhanced methyl blue adsorption

This work reports the incorporation of coordinated water into Ni-BTC nanorods (Ni-BTC-O) which induces their structural transformation to Ni-BTC nanofibres (Ni-BTC-F). The carbonization of the NiBTC nanofibres at 600 degrees C results in the formation of carbon nanotube (CNT)-decorated hierarchical porous nickel/carbon hybrid (labelled as Ni/C-600) with enlarged pores. In contrast, the Ni/C hybrid obtained from the carbonization of the original (unmodified) Ni-BTC nanorods (Ni-BTC-O) at 600 degrees C (labelled as Ni-BTC-O-600) exhibits smaller pore size and does not show the formation of CNTs. The Ni/C-600 hybrid derived from Ni-BTC-F shows a very high adsorption capacity of 686.8 mg g-1 toward methyl blue (MB) dye. This is approximately 4.8 times higher than the adsorption capacity of Ni-BTC-O-600 (144.1 mg g-1). The higher adsorption performance of Ni/C-600 relative to Ni-BTC-O-600 can be attributed to its larger pore volume, hierarchical porosity, and additional adsorption sites provided by the CNTs. In addition, the Ni/C-600 hybrid can maintain 90% of its adsorption capacity after 5 consecutive cycles, demonstrating its potential as an efficient and recyclable adsorbent for MB dye. (c) 2023 Elsevier Inc. All rights reserved.