Reactive Template-Derived CoFe/N-Doped Carbon Nanosheets as Highly Efficient Electrocatalysts toward Oxygen Reduction, Oxygen Evolution, and Hydrogen Evolution

Abstract

The increasing need for clean and sustainable energy inspires researchers to explore low-cost nonprecious metal electrocatalysts for advanced energy storage and conversion. Herein, we develop a reactive template route to fabricate a high-efficiency oxygen reduction reaction (ORR)/oxygen evolution reaction (OER)/hydrogen evolution reaction (HER) trifunctional electrocatalyst (CoFe/NH-C NS) via pyrolyzing the mixture containing CoFe-layered double hydroxide@glucosaminoglycan (CoFe-LDH@p-Glu) and urea/dicyandiamide. In this strategy, the CoFe-LDH not only provides a well-defined two-dimensional template to form carbon NSs but also employs a well-distributed CoFe precursor to form uniform CoFe nanoparticles (NPs). Such a synthetic strategy has been demonstrated effective to controllably fabricate the special nanostructure with metal NPs embedded in N-doped carbon NSs and favorable exposure of active sites, leading to a strong synergistic effect between CoFe and N-doped carbon NSs and abundant electrocatalytic active sites for energy electrocatalysis. CoFe/NH-C NS exhibits superior ORR performances to Pt/C with more positive half-wave potential (844 mV for CoFe/NH-C NS vs 832 mV for Pt/C), longer stability, and better methanol tolerance in alkaline conditions. Furthermore, CoFe/NH-C NS displays an identical current density to commercial RuO2 at 1.8 V (vs RHE) toward OER and a remarkable electrocatalytic property toward HER in alkaline conditions. This work presents fresh strategies for the design and fabrication of high-performance carbon-based energy materials.

Chemical Identification of Catalytically Active Sites on Oxygen‐doped Carbon Nanosheet to Decipher the High Activity for Electro‐synthesis Hydrogen Peroxide

“…[42,47] TheR aman spectra (Figure 2b)s how that all prepared samples exhibit typical Da nd Gb and at 1340 cm À1 and 1597 cm À1 ,respectively. [48] Theintensity ratio of Dband to G band (I D /I G )i ncreases with the elevated carbonization temperature,indicating the higher carbonization temperature may create more defects on carbon matrix. TheX -ray absorption near-edge spectroscopy (XANES) measurements were carried out to acquire the chemical bonding configuration information.…”

Chemical Identification of Catalytically Active Sites on Oxygen‐doped Carbon Nanosheet to Decipher the High Activity for Electro‐synthesis Hydrogen Peroxide

“…[42,47] TheR aman spectra (Figure 2b)s how that all prepared samples exhibit typical Da nd Gb and at 1340 cm À1 and 1597 cm À1 ,respectively. [48] Theintensity ratio of Dband to G band (I D /I G )i ncreases with the elevated carbonization…”

“…[44,58,59] As shown in Figure S15,16, the ECSA of the titrated samples is much smaller than that of the primal OCNS 900 ,indicating the titration reactions for the oxygenated functional groups deactivate the corresponding catalytically active sites. [48,60,61] Besides,t he invariable I D /I G values (Raman spectra in Figure S17) before and after titration experiment indicate that titration reactions for the oxygen functional groups have no effect on the defect structure of carbon matrix.…”

Core‐shell FeCo N‐doped biocarbons as stable electrocatalysts for oxygen reduction reaction in fuel cells

“…The prepared Fe x Co 100-x @N-doped C samples with different FeCo alloyed ratios possess the comparable nitrogen contents (ie, 1.0-1.6 at%) on the surface and the peaks are fitted to 398.2, 399.3, 399.8, 400.1, 401.9 and 402.9 to 404.3 eV, which are ascribed to pyridinic-N, amino-N, Fe/Co-N, pyrrolic-N, graphitic-N and oxidized-N, respectively. Based on the latest works, [59][60][61] pyridinic-N, graphitic-N and Fe/Co N are reported to be active sites toward ORR on N-doped carbons. Consequently, the Fe 50 Co 50 @Ndoped C electrocatalysts have the highest total amounts of these active sites (ie, 88.5%, see Table 2) with a higher total N content (1.9%, see Table 1).…”