Low-crystalline transition metal oxide/hydroxide on MWCNT by Fenton-reaction-inspired green synthesis for lithium ion battery and OER electrocatalysis

Transition metal oxides (TMOs) have versatile applications in emerging electrochemical energy storage and conversion technologies. However, their low intrinsic conductivity remains a major hurdle to be overcome. An effective strategy is to make thin coatings of TMOs on a conducting substrate with high surface area, such as carbon nanotubes (CNTs) and graphene. The preparation of such composites usually involves functionalization of the carbon materials and the current methods commonly require hazardous chemicals, high energy consumption and thus pose environmental concerns. We hereby report Fenton-reaction-inspired synthesis as a green and facile alternative to make composites of MWCNT with TMO or layered double hydroxide (LDH). The resulting Fe₂O₃/MWCNT composite shows high capacity, superior rate and cycle performance as an anode material for lithium ion battery. Similarly-prepared NiFe LDH/MWCNT composite exhibits high OER electrocatalytic activity and ultra-high stability. The high electrochemical performances in both cases are attributed to the nanosized low crystalline oxide/hydroxide particles anchored on the conducting MWCNT scaffold. This facile yet effective synthesis method features three principles in green chemistry, i.e., pollution prevention, less hazardous chemicals, and high energy efficiency. It marks a generic approach that is also applicable to other transition metals such as manganese and cobalt.