Nitrogen-doped Electrocatalysts Research Articles

Hierarchical Co/MoO2@N-doped carbon nanosheets derived from waste lotus leaves for electrocatalytic water splitting

It is imperative for electrochemical water splitting to seek functional materials with high performance, competence, durability, economical, and eco-friendly. Herein, we develop a simplistic two-step annealing strategy to synthesize the hierarchical Co/MoO 2 @nitrogen (N)-doped carbon nanosheets (CMO@NC) electrocatalysts derived from the low-cost and sustainable lotus leaves biomass for water-splitting. The optimum catalyst (CMO@NC/450) exhibits a notable low overpotential of 130 and 272 mV at a current density of 10 mA cm −2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH, owing to their unique surface features, large surface area, abundant meso/micropores, and high pyridinic N-contents. Also, the CMO@NC/450 catalyst-equipped with a two-electrode configuration exhibits notable water splitting activity only requires a cell-potential of 1.629 V@10 mA cm −2 in 1.0 M KOH. The results reveal that hierarchical flower-like morphology increases the contact area, prevents aggregation, and enables massive active-sites for HER and OER. Additionally, the synergistic effects between Co/MoO 2 and the N-doped-carbon heterostructure enhance charge-delocalization, ultimately improving electrocatalytic performance and stability. This work is aimed to promote the exploration and design of suitable doping structures and compositions for the development of highly effective and sustainable biomass-derived catalysts in a wide-range of electrochemical applications. A hierarchical Co/MoO 2 @NC nanosheets electrocatalyst derived from the low-cost and sustainable Lotus leaves biomass exhibits robust stability and good alkaline HER and OER activity. Lotus leaves biomass, developed as a particular structure and nitrogen-doped electrocatalyst, show significant water splitting performance. • Hierarchical Co/MoO 2 @NC are successfully fabricated from waste lotus leaves. • Electrocatalyst exhibits enhanced activity for HER and OER in alkaline media. • Lotus leaves biomass is a green, economical and sustainable precursor of N-doped C. • Self-N-doped carbon and rich pyridinic-N can efficiently improve catalytic activity.

Short-route synthesis method of N-doped exfoliated graphite whit catalytic activity for the oxygen reduction reaction

AbstractWe report the synthesis of metal-free nitrogen-doped electrocatalysts obtained from graphite and urea as carbon and nitrogen precursor, respectively. High-energy milling and thermal annealing were carried out to obtain low cost electrocatalysts. Additionally, this method has shorter synthesis times, is environmentally friendly and use high-availability raw materials. A short-route synthesis consisted in the partial exfoliation of graphite by mechanical milling with urea. Afterwards, nitrogen was integrated into the exfoliated graphite lattice by thermal annealing at 500°C. XPS analyses shows up to 1.7 at. % was incorporated to the graphitic lattice. Scanning Electron Microscopy, X-ray diffraction and Raman Spectroscopy were used to analyse the morphology and structural features. The catalytic activity for the oxygen reduction reaction in basic media was evaluated by the rotating disk electrode technique.

A nitrogen-doped electrocatalyst from metal–organic framework-carbon nanotube composite

Abstract