Catalysis Today, Vol.370, 46-54, 2021
An adept approach to convert titanium carbide to titanium nitride and it's composite with N-doped carbon nanotubes for efficient oxygen electroreduction kinetics
We report an in situ synthesis of titanium nitride (Ti3N2Tx) from its carbide (Ti3C2Tx) and concurrently composite formation with N-doped carbon nanotubes (N-CNTs). Unlike conventional wet-chemical method, a simple approach has been adopted for the synthesis of Ti3N2Tx and it's composite with N-CNTs. The crystallographic study shows an obvious phase transformation from carbide to nitride. Importantly, an optimized composite electrocatalyst (Ti3N2@NCNT(20)-800) exhibits promising oxygen reduction ability under alkaline conditions with positive onset potential (Eonset) of 1.0 V versus reversible hydrogen electrode (RHE) and current density (JL) of 5.3 mA/cm2. The remarkable oxygen reduction reaction (ORR) properties mainly originate from the fascinating carbon-nitrogen exchange (Ti3C2Tx into Ti3N2Tx) in the MXene lattice along with N-doping in CNTs, which eventually lead to the formation of their composite and generating enough active centres for dioxygen adsorption followed by electroreduction. Moreover, the rotating ring disk electrode (RRDE) studies were carried to particularly detect peroxide (HO2 ) formation and further to get an insight into ORR kinetics. Additionally, a robust performance of Ti3N2@NCNT(20)-800 electrocatalyst over Pt/C has been observed during the electrochemical cycling stability up to 10,000 (10 k) durable cycles. Thus, we believe that the present methodology provides an adept approach to convert carbide into nitride and further to extend it to synthesize the MXene based composite materials for energy conversion applications.