Trace Metal Loading of B‐N‐Co‐doped Graphitic Carbon for Active and Stable Bifunctional Oxygen Reduction and Oxygen Evolution Electrocatalysts

Abstract

Understanding the structure-property relations of non-precious metal heteroatom co-doped carbon electrocatalysts exhibiting high activity as well as long-term durability for both ORR and OER remains challenging but is indispensable for the development of bifunctional ORR/OER electrocatalysts. We propose B-N-co-doped graphitic 2D carbon nanostructures impregnated with controlled amount of transition metals (M-BCN; M=Co, Ni, Fe, Cu) as bifunctional ORR/OER electrocatalysts. Co-BCN outperformed the Ni-, Fe-, Cu-based BCN catalysts exhibiting potential values of 0.87 V and 1.62 V at À 1 mA/cm 2 and 10 mA/ cm 2 during ORR and OER, respectively. Importantly, Co-BCN shows bifunctional cyclic stability (Δη; E OER À E ORR = 0.75 V) of up to 300 cycles in 1 M KOH for a duration of 20 h with total activity loss of only 10.2 % (ORR) and 6.2 % (OER), respectively. A low loading of the metal precursors was used to preserve porosity and to facilitate the formation of metal nanoparticles or MÀ N x B/C type species embedded in the graphitic carbon layers. The B-N-co-doped graphitic layers also protect the embedded metal nanoparticles explaining the observed longterm stability.

Electrochemically Tuned Synergistic Nano‐Interface of a Tertiary Ni(OH)2−NiO(OH)/NixP Heterojunction Material for Enhanced and Durable Alkaline Water Splitting

“…The interconnected network‐like structure of NOPO that enhanced the electrolyte diffusion is responsible for highly enhanced OER performance. The OER activity of NOPO is similar to, or better than various other transition metal or metal oxide‐based electrocatalysts in alkaline solution, such as NiO‐C 6 F 5 , [55] Co 3 O 4 , [56] PtCo, [56] LiCoO 2 , [57] Mn x O y (Co x O y )/N‐doped carbon, [58] Ni‐BCN, [59] and Fe‐BCN, [59] a comparative study of which has been summarized in Table 3.…”

MnFeNi‐Based Composite as a Case Study of a Bifunctional Oxygen Electrocatalyst under Dynamically Changing Electrode Potentials

“…[14,15] Such materials are unsuitable for applications that require operation under dynamic ORR/OER conditions as it is for reversible energy conversion and storage devices. [16] Different strategies have been proposed with the aim of preventing activity loss of BOEs at alternating ORR/OER conditions, including the use of decoupled electrochemical cell configurations where the ORR and OER electrode films are used independently from each other, [10,17] the exploitation of synergistic effects between metal components in the ORR and OER active sites, [11,14,18] the fine control of size and distribution of catalyst particles embedded within the catalyst support, [19,20] and the incorporation of stability promoters into catalyst composites. [21] Corrective strategies have also been explored with the aim of restoring, at least partially, the catalytic properties of oxygen electrocatalysts after operation.…”

Electrocatalytic Oxidation of Urea and Ethanol on Two-Dimensional Amorphous Nickel Oxide Encapsulated on N-Doped Carbon Nanosheets

“…However, noble metal-based catalysts (IrO 2 and RuO 2 ) show excellent OER activity, but their high cost, low abundance, and unsatisfying stability hinder large-scale production and thus limit the goal of a sustainable society . Numerous efforts have been taken to promote the OER, − but traditional problems, such as the need for a high input voltage to drive the OER in water electrolysis and the production of less value O 2 , which can combine with the H 2 produced at the cathode by gas cross-over to create explosive dangers, are problematic for advancement . Additionally, the presence of H 2 , O 2 , and electrocatalysts may result in the creation of reactive oxygen species (ROS), which may damage the membrane and shorten the electrolyzer’s lifespan …”