B, N‐codoped Cu–N/B–C Composite as an Efficient Electrocatalyst for Oxygen‐Reduction Reaction in Alkaline Media

Abstract

As an alternative for platinum‐based electrocatalysts, the development of non‐precious metal catalysts for oxygen reduction reaction (ORR) is highly desirable for fuel cell applications. In this paper, we propose a facile preparation method for a B, N‐codoped Cu–N/B–C nanomaterial as an efficient electrocatalyst for ORR in alkaline electrolytes. One‐step heat treatment of cyanamide/melamine, boric acid, and cupric chloride loaded on carbon black produces a Cu–N/B–C composite with a high specific surface area. The Cu–N/B–C‐800 composite pyrolyzed at 800 °C has the best ORR performance among all tested composites. Cu–N/B–C‐800 saw an ORR onset potential at 0.95 V and a half‐wave potential (E1/2) at 0.84 V vs. reversible hydrogen electrode (RHE) in 0.1 M KOH solution, which is comparable to the commercial 20 wt% Pt/C catalyst. Moreover, Cu–N/B–C‐800 has a small negatively shifted E1/2 value (−8.0 mV) under the accelerated‐durability test condition, demonstrating superior stability and higher tolerance to the methanol‐crossover effect compared with the Pt/C catalyst. Furthermore, the anion exchange membrane fuel cell (AEMFC) loaded with Cu–N/B–C‐800 as the cathode catalyst has an open cell voltage of 0.85 V and a peak power density of 80 mW/cm2 at 60 °C without backpressure, which is in the list of optimal non‐precious metal catalysts for ORR in AEMFC.

Fe, B, and N Codoped Carbon Nanoribbons Derived from Heteroatom Polymers as High-Performance Oxygen Reduction Reaction Electrocatalysts for Zinc–Air Batteries

“…High-resolution N 1s XPS spectra of as-synthesized catalysts could be fitted into five peaks, which belonged to pyridinic N (398.0 eV), Fe–N (399.2 eV), pyrrolic N (400.1 eV), graphitic N (400.8 eV), and oxidized N (402.1 eV) (Figure b). − Notably, pyridine nitrogen, Fe–N x , and graphite nitrogen accounted for the largest proportion of Fe–B–N–C. Previous studies have shown that pyridine nitrogen and graphite nitrogen have a decisive effect on the formation of Fe–N x and promoted the four-electron process of ORR. , As shown in Figure c, high-resolution B 1s XPS spectra showed the three valence states of B, involving B–N–C (189.2 eV), BC 3 (190.7 eV), and B–O (191.6 eV) in Fe, B, N codoped, and B, N codoped samples. , Among them, the 3-fold-coordinated BC 3 phase can promote the ORR performance due to its strong electron-donor ability . In addition, the interaction between adjacent B and N atoms could promote the charge transfer of adjacent carbon atoms, facilitate the adsorption of O 2 , and weaken the OO bond. ,, The high-resolution Fe 2p XPS spectra of Fe–B–N–C and Fe–N–C (Figure d) showed the existence of Fe 3+ (712.5 and 725.3 eV) and Fe 2+ (710.2 and 723.3 eV) peaks .…”

“…The chemical state of various atoms was investigated by X-ray photoelectron spectroscopy (XPS). As shown in Figure S4, the XPS survey spectrum of Fe−B−N−C catalysts showed the presence of Fe 55,56 Among them, the 3-fold-coordinated BC 3 phase can promote the ORR performance due to its strong electron-donor ability. 57 In addition, the interaction between adjacent B and N atoms could promote the charge transfer of adjacent carbon atoms, facilitate the adsorption of O 2 , and weaken the OO bond.…”

Recent Advances in Non‐Precious Metal Single‐Atom Electrocatalysts for Oxygen Reduction Reaction in Low‐Temperature Polymer‐Electrolyte Fuel Cells

“…While iron, cobalt and manganese are the most utilised transition metals to prepare SACs for the AEMFC cathode as was evident from prior, then in recent years good performance in single-cell AEMFC tests has also been obtained with other cheap and widely available metals, such as zinc and copper (see Table 2). [182,[184][185][186] Zinc has been mostly used in the preparation of FeÀ NÀ C single-atom electrocatalysts, whether to modify the porous structure with ZnCl 2 or using ZIF-based MOFs, and then removing the zinc as unwanted weight as it is mostly shown to be rather inactive towards the ORR. However, recently Sun et al [182] showed both theoretically via DFT calculations and experimentally that atomically dispersed Zn-sites could indeed be ORR-active if Zn is combined with pyrrolic-N moieties.…”

Alkaline membrane fuel cells: anion exchange membranes and fuels

“…20 A B,N-codoped Cu-N/B-C nanomaterial was prepared as an ORR catalyst in alkaline electrolytes, which demonstrated superior stability and higher tolerance to methanol crossover in comparison to Pt/C catalyst, and was also shown to have suitable properties for use in an AEMFC. 58 Microstructure and the fabricating method of electrodes associated with their transport resistances and electrochemical kinetics are critical for the improvement of cell performance. Modern AEMFC electrocatalyst layers are usually composite structures of anion conducting ionomer material and noble or non-noble metal catalyst, usually supported on carbon.…”