Boron‐ and Iron‐Incorporated α‐Co(OH)₂ Ultrathin Nanosheets as an Efficient Oxygen Evolution Catalyst

Abstract

Electrochemical water splitting is a critical technology for various energy storage and conversion devices, but it is greatly restricted by the sluggish kinetics of the oxygen evolution reaction (OER). Herein, an effective electrocatalyst of boron-and iron-incorporated a-Co(OH) 2 (B-a-Co 5.8 Fe LDH)ultrathin nanosheets was synthesized for the OER by using sodium tetraphenylborate (NaTPB) as a mild alkali and boron source in ethylene glycol/water system (EG-W). Benefiting from the large accessible surface area (563 m 2 g À1 ) and the synergistic effect of CoÀFeÀB,the catalyst (B-a-Co 5.8 Fe LDH) exhibits improved activity and stability in 1 M KOH solution with a low overpotential (264 mV at 10 mA cm À2 ) and Tafel slope (34 mV dec À1 ). In addition, this method was also applied to fabricate boronand iron-incorporated a-Ni(OH) 2 . This study should inspire a new pathway to design highly efficient OER catalysts.The growing global energy demand, coupled with the depletion of fossil fuels and the related negative environmental impact, is stimulating intense research of various types of clean and sustainable energy conversion and storage technologies with high efficiency, low cost, and environmental benignity. [1] The oxygen evolution reaction (OER) plays an important role in sustainable energy systems such as water splitting technologies and metal-air batteries. [2] However, OER is influenced by the high overpotential due to the intrinsically sluggish kinetics. [3] Thus, it is essential to accelerate the reaction, lower the overpotential and improve the energy conversion efficiency of OER by catalysts. Although noble metal oxides, including IrO 2 and RuO 2 , are very active and durable electrocatalysts for OER, they are difficult to scale up due to their limited reserves and high cost. [4] Therefore, the non-precious transition metal and their compounds, especially Fe, Co and Ni, have been extensively used as OER catalysts because of their competitive activity and earth-abundance. [5] Among these active materials, two-dimensional (2D) layered double hydroxide (LDH) com-posed of edge-sharing MO 6 octahedral layers has aroused increasing interests due to their large surface area and open layered structure, e. g. CoFe, [6] CoZn, [7] CoNi, [8] NiFe, [9] CoMn [10] nanosheets etc.Alpha type cobalt hydroxide (a-Co(OH) 2 ) with layered hydrotalcite-like structure consisting of host layers and intercalated molecules is of good conductivity, which is considered as an ideal electrocatalyst for OER. But a-Co(OH) 2 is instable and easy to transform into b-Co(OH) 2 , leading to the inferior OER performance. [6d] In order to improve activity and stability of the a-Co(OH) 2 , some effective strategies have been proposed. For instance, Wang et al. increased the activity of a-Co(OH) 2 towards the OER by incorporating Fe; [6d] Kim et al. fabricated a-Co(OH) 2 on Ag nanowires to improved activity for OER with a reduced onset potential of 220 mV and superior durability; [11] Yang et al. also demonstrated that chlorine intercalate...

Defect Engineering of Cobalt-Based Materials for Electrocatalytic Water Splitting

“…Recently, a large number of experiments have suggested that many electrocatalysts show better activity after being doped with many common heteroatoms (nonmetal atoms: F, O, S, N, P, B, and metal atoms Fe, Co, Ni, Cu, Mn, Zn, etc. ). ,,− In this chapter, we mainly summarize the influence of catalytic activity about metal and nonmetal heteroatomic dopants.…”

“…Except for the single species of heteroatom doping, multiple heteroatoms were also explored by researchers in water splitting. For instance, Liu and co-workers also prepared a boron and iron contemporary-doped Co-base catalyst, which was synthesized by using sodium tetraphenylborate (NaTPB) as a mild alkali and boron source in an ethylene glycol/water system. Sun and co-workers synthesized N, P, and F tridoped CoFe 2 O 4 with specifically an ionic liquid as a dopant, which is a new way for doping heteroatoms.…”

Ultrahigh oxygen evolution reaction activity in Au doped co-based nanosheets

“…10,31 Co 2p 3/2 has a red shi of 0.3 eV with the coated Au on Co(OH) 2 NSs. The increased Co 3+ /Co 2+ ratio in Au-Co(OH) 2 NSs demonstrates that Au coating increases the Co valence in Co(OH) 2 , which was resulting from the low coordinated Co-O bonding because of the appearance of Au.…”

Co-Based Nanosheets with Transitional Metal Doping for Oxygen Evolution Reaction

“…Fe 1 Co 1 O x ANSs possess an overpotential of ca. 240 mV, which is better than other MCoO x ANSs ( Table S1 ) and the state-of-art Co-based OER catalysts ( Table S2 ) [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. The higher mass activity shows the lower cost of OER catalysts in practical applications.…”

“…The Co feed amount in these materials is 0.4 mmol; Table S1: Parameter of electrocatalysts for OER in 1 M KOH; Table S2: Collection of reported Co-based electrocatalysts on glassy carbon electrode for OER in 1 M KOH. References [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ] are cited in the supplementary materials.…”