Dual-template synthesis of CoNi alloy nanoparticles anchored on N-doped carbon nanotubes for efficient oxygen reduction reaction

SummaryEfficient electrocatalyst toward hydrogen evolution/oxidation reactions (HER/HOR) and oxygen reduction reaction (ORR) is desirable for water splitting, fuel cells, etc. Herein, we report an advanced platinum phosphide (PtP2) material with only 3.5 wt % Pt loading embedded in phosphorus and nitrogen dual-doped carbon (PNC) layer (PtP2@PNC). The obtained catalyst exhibits robust HER, HOR, and ORR performance. For the HER, a much low overpotential of 8 mV is required to achieve the current density of 10 mA cm−2 compared with Pt/C (22 mV). For the HOR, its mass activity (MA) at an overpotential of 40 mV is 2.3-fold over that of the Pt/C catalyst. Interestingly, PtP2@PNC also shows exceptional ORR MA which is 2.6 times higher than that of Pt/C and has robust stability in alkaline solutions. Undoubtedly, this work reveals that PtP2@PNC can be employed as nanocatalysts with an impressive catalytic activity and stability for broad applications in electrocatalysis.

In situ synthesis of CoFe2O4 nanoparticles embedded in N-doped carbon nanotubes for efficient electrocatalytic oxygen reduction reaction

Confined pyrolysis synthesis of N-doped carbon-supported FePr nanoparticles for efficient oxygen reduction based on 3d–4f orbital coupling

Cerium oxide boosted CoFe-N codoped carbon nanotubes with abundant oxygen-vacancies toward efficient oxygen reduction and methanol oxidation reaction

Enabling highly efficient electrocatalytic oxygen reduction and evolution reaction by established strong MnO/Co-support interaction

Rational designs of electrocatalytic active sites and architectures are of great importance to develop cost-efficient non-noble metal electrocatalysts towards efficient oxygen reduction reaction (ORR) for high-performance energy conversion and storage devices. In this work, active amorphous Fe-based nanoclusters (Fe NC) are elaborately embedded at the inner surface of balloonlike N-doped hollow carbon (Fe NC/Ch sphere) as an efficient ORR electrocatalyst with an ultrathin wall of about 10 nm. When evaluated for electrochemical performance, Fe NC/Ch sphere exhibits decent ORR activity with a diffusion-limited current density of ∼5.0 mA/cm2 and a half-wave potential of ∼0.81 V in alkaline solution, which is comparable with commercial Pt/C and superior to Fe nanoparticles supported on carbon sheet (Fe NP/C sheet) counterpart. The electrochemical analyses combined with electronic structure characterizations reveal that robust Fe−N interactions in amorphous Fe nanoclusters are helpful for the adsorption of surface oxygen-relative species, and the strong support effect of N-doped hollow carbon is benefitial for accelerating the interfacial electron transfer, which jointly contributes to improve ORR kinetics for Fe NC/Ch sphere.

An efficient oxygen reduction reaction (ORR) catalyst based on a three dimensional holey graphene framework with precise localization of N-doped carbon nanotubes (N-CNTs) on the hole-edges of graphene is demonstrated.

Uniform, Scalable, High-Temperature Microwave Shock for Nanoparticle Synthesis through Defect Engineering

Developing inexpensive, efficient and good stability transition metal-based oxygen reduction reaction (ORR) electrocatalysts is a research topic of great concern in the commercial application of fuel cells. Herein, with zinc nitrate as activator, iron nitrate as active component and melamine as intercalating agent and nitrogen source, an N-doped porous carbon supported Fe/Fe3O4 (Fe/Fe3O4@NC) catalyst is successfully synthesized by an impregnation–calcination method combined with freeze-drying technique. The positive onset potential (Eonset), half-wave potential (E1/2) and limiting current density (JL) of the optimal Fe/Fe3O4@NC catalyst are 1.012, 0.90 V vs. RHE and 5.87 mA cm−2, respectively. Furthermore, Fe/Fe3O4@NC catalyzes ORR mainly through a 4e− pathway, and the yield of H2O2 is less than 5%. It also manifests a robust stability after 5000 CV cycles of ADT testing, and the half-wave potential is only negatively shifted 17 mV. The structural characterization and experimental results further suggest that the outstanding ORR electrocatalytic performance of the Fe/Fe3O4@NC catalyst benefits from the synergetic effect of zinc nitrate activation and nitrogen doping, which can greatly improve the specific surface area, thus better dispersing more metal active sites. This work puts forward a simple and practicable way for preparing high-performance non-noble metal-based biomass ORR electrocatalysts.

Amidst depleting traditional energy resources and pressing demands for sustainable technologies, developing efficient, low-cost and pH-universal oxygen reduction reaction (ORR) catalysts is crucial for advancing fuel cells and metal-air battery. Currently, Pt-based materials represent the most efficient electrocatalysts for ORR, yet their commercial deployment is constrained by high costs and moderate stability. In this work, we successfully encapsulated SnSb alloy nanoparticles in N-doped porous carbon using 4,5-dicyano-2-aminoimidazole as a dual-functional molecular precursor with sacrificial MgO templates, achieving nanolevel metal dispersion and alloy-carbon coupling. The catalyst, incorporating N-doped porous carbon with a high specific surface area and nanosized SnSb alloy as active sites, exhibits outstanding ORR activity with half-wave potentials (E1/2) of 0.87 V in 0.1 M KOH, 0.76 V in 0.1 M PBS, and 0.67 V in 0.5 M H2SO4, which DFT calculations attribute to favorable d-band modulation and optimized intermediate adsorption from Sn-Sb synergy. In zinc-air battery, the catalyst delivers a peak power density of 169 mW·cm-2 and an energy density of 848.8 Wh·kgZn-1 at 10 mA·cm-2, markedly higher than Pt/C benchmarks, confirming its significant potential for practical energy-conversion devices.

Metal-organic frameworks derived cobalt encapsulated in porous nitrogen-doped carbon nanostructure towards highly efficient and durable oxygen reduction reaction electrocatalysis

Efficient, stable, and low-cost oxygen reduction catalysts are the key to the large-scale application of metal-air batteries. Herein, high-dispersive Fe2O3 nanoparticles (NPs) with abundant oxygen vacancies uniformly are anchored on lignin-derived metal-nitrogen-carbon (M-N-C) hierarchical porous nanosheets as efficient oxygen reduction reaction (ORR) catalysts (Fe2O3/M-N-C, M═Cu, Mn, W, Mo) based on a general and economical KCl molten salt-assisted method. The combination of Fe with the highly electronegative O induces charge redistribution through the Fe-O-M structure, thereby reducing the adsorption energy of oxygen-containing substances. The coupling effect of Fe2O3 NPs with M-N-C expedites the catalytic activity toward ORR by promoting proton generation on Fe2O3 and transfer to M-N-C. Experimental and theoretical calculation further revealed the remarkable electronic structure evolution of the metal site during the ORR process, where the emission density and local magnetic moment of the metal atoms change continuously throughout their reaction. The unique layered porous structure and highly active M-N4 sites resulted in the excellent ORR activity of Fe2O3/Cu-N-C with the onset potential of 0.977V, which is superior to Pt/C. This study offers a feasible strategy for the preparation of non-noble metal catalysts and provides a new comprehension of the catalytic mechanism of M-N-C catalysts.

Co nanoparticles and ZnS decorated N, S co-doped carbon nanotubes as an efficient oxygen reduction catalyst in zinc-air batteries

Morphology-controlled synthesis of ternary Pt–Pd–Cu alloy nanoparticles for efficient electrocatalytic oxygen reduction reactions

Surface-oxidized Fe–Co–Ni alloys anchored to N-doped carbon nanotubes as efficient catalysts for oxygen reduction reaction