Efficient oxygen electroreduction kinetics by titanium carbide@nitrogen doped carbon nanocomposite

Abstract

A simple approach towards preparation of non-noble metal electrocatalyst for oxygen reduction reaction in low temperature fuel cells has been necessity for a sustainable green technology. Herein, a cost-effective and facile method of preparation of TiC@N-doped graphene like carbon nanocomposite (TiC@NC) has been discussed. The composite structure of as-prepared TiC@NC was confirmed using structural analysis and morphological studies. Interestingly, the optimized TiC@NC(0.2)-800 electrocatalyst shows remarkable oxygen reduction reaction (ORR) kinetics with better onset potential +1.08 vs RHE and significant current density of 4.8 mA/cm2 in alkaline medium. Further, obtained catalyst exhibits four electron transfer mechanism similar to Pt-based electrocatalysts. Additionally, TiC@NC(0.2)-800 shows better mass activity (∼410 mA/mg) as compared to other compositions. Moreover, the single step kinetics mechanism has been seen due to lower (<5%) peroxide yield. The relatively lower charge transfer resistance at electrode/electrolyte interface of TiC@NC (0.2)-800 electrode supports for higher catalytic activity. Additionally, electrochemical cycling reveals the better stability by TiC@NC(0.2)-800 even after 10,000 cycles (10 mV negative shift in E1/2) than that of state of art Pt/C catalyst (80 mV negative shift in E1/2). The presence of N-doped carbon around TiC crystals is responsible for better electrocatalytic activity (due to optimal doping synergy), though the support of TiC makes the electrocatalyst more stable in nature (thanks to strong TiC-NC interactions). Additionally, TiC@NC(0.2)-800 does not show any response towards methanol oxidation reaction, annulling the cross-over effects. Hence, TiC@NC(0.2)-800 could be hopeful substitute for conventional Pt/C electrocatalyst for energy conversion.