Inhibiting solubility challenges: Carbon nanotube encapsulation of stable transition metal oxides for electrochemical energy storage and conversion applications

Abstract

Transition metal oxides (TMO) are commonly used catalyst materials for electrolytic water splitting. However, their solubility in alkaline electrolytes presents a significant challenge, reducing their catalytic activity. To address this issue, we have developed a technique to synthesize carbon nanotube (CNT) encapsulated Fe2O3, effectively inhibiting the dissolution of Fe2O3. The formation of Fe2O3@CNT not only provides an efficient pathway for electron transfer, but also increases its active surface area. The results demonstrate that the excellent catalytic performance of Fe2O3@CNT in both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with overpotentials of 249 mV and 208 mV, respectively. Moreover, the CNT encapsulation technique exhibits universality, as evidenced by Co3O4@CNT, which displays a specific capacitance of 1800 F g−1 at 1 A g−1, and retains 125.5 % of its initial capacitance after 9000 cycles in a two-electrode system. Overall, our study highlights the role of CNT encapsulation in promoting the catalytic and energy storage performance of TMO, revealing a novel approach to enhancing their stability.