Amorphous Fe–Ni–P–B–O Nanocages as Efficient Electrocatalysts for Oxygen Evolution Reaction

Abstract

Electrocatalysts are one of the most important parts for oxygen evolution reaction (OER) to overcome the sluggish kinetics. Herein, amorphous Fe-Ni-P-B-O (FNPBO) nanocages as efficient OER catalysts are synthesized by a simple low-cost and scalable method at room temperature. The samples are chemically stable, in clear contrast to reported unstable or even pyrophoric boride samples. The Fe/Ni ratio of the FNPBO nanocages can be continuously adjusted to optimize the OER catalytic performance. The FNPBO nanocages composed of multicomponent elements can weaken the metal-metal bonds thus rearranging the electron density around the catalytic metal atom centers and reducing the energy barrier for intermediate formation. Hence the optimized FNPBO (Fe6.4Ni16.1P12.9B4.3O60.2) catalyst shows superior intrinsic electrocatalytic activity for OER. The low overpotential to afford the current density of 10 mA cm -2 (236 mV), the small Tafel slope (39 mV dec -1 ), and the high specific current density (26.44 mA cm -2 ) at a given overpotential of 300 mV make a sharp contrast to state-of-the-art RuO2 (327 mV, 136 mV dec -1 , and 0.028 mA cm -2 , respectively). Clean energy is highly desired for clean and sustainable future. [1][2][3] Hydrogen has been considered as an ideal alternative fuel to replace gasoline, which is environmental friendly with a

Understanding and Optimizing Ultra‐Thin Coordination Polymer Derivatives with High Oxygen Evolution Performance

“…To prepare the low cyrstalline and ultra‐thin R‐Ni 10−x Fe x ‐CP nanosheets, NaBH 4 was chosen as a reductant to produce structural deficiencies and distortions (see Experimental details in the Supporting Information). [ 19,23,31–33 ] The PXRD patterns (Figure S7, Supporting Information) of R‐Ni 10−x Fe x ‐CPs (0 ≤ x ≤ 5) showed low crystallinity with main diffraction peaks at 2θ ≈ 15.5° and 26.8°, which correspond to the (012) and (110) planes of a Ni(OH) 2 ·0.75H 2 O reference (JCPDS No. 38–0715), respectively.…”

“…Notably, no B signal was detected from the XPS B1s spectra of R‐NiFe‐CPs (Figure S36, Supporting Information), which is further implying that R‐NiFe‐CPs emerged from the proposed reaction mechanism (see Experimental details in the Supporting Information, Tables S2 and S4, Supporting Information). [ 19,23 ] Noteworthy, the binding energy of Ni 2p in R‐NiFe‐CPs exhibited a negative shift around 0.91 eV compared with that of NiFe‐LDH (Figure 3d). For the XPS spectrum of O 2s in NiFe‐LDH (Figure 3e), three main peaks located at 529.68, 531,39, and 532.98 eV, respectively, are assigned to metal‐oxygen bonds, surface hydroxyl groups, and adsorbed water.…”

“…Ni‐CPs and R‐Ni‐CPs were employed as reference catalysts here, because the substitution of Fe may either promote or diminish the OER activity, depending on the Fe content. [ 23,37,65–67 ] Therefore, the effects of varying the Ni/Fe atomic ratio on the OER performance were first investigated (Figure S38, Supporting Information). A 90% iR‐correction was performed to evaluate all cyclic voltammetry (CV) measurements (Figure S39, Supporting Information).…”

“…As presented in Figure S38, Supporting Information, the OER activities of the catalyst series exhibited a significant volcano trend as a function of the atomic ratio of Ni/Fe, which is consistent with previous studies on NiFe‐based catalysts. [ 23,37,65–67 ] The best OER performance was observed in the samples with 20% Fe substitution, referred to herein as R‐NiFe‐CPs (see Section 2.2.). After optimizing the mass loading of as‐prepared catalysts, the electrodes with 0.4 mg cm −2 exhibited the best OER activity (Figure S40, Supporting Information).…”

“…Moreover, CPA‐ or CP‐derived compounds have recently emerged as new competitive candidates compared to many of the state‐of‐the‐art transition metal‐based electrocatalysts. [ 19–24 ] Despite these tremendous achievements on CPAs and CPs, their straightforward construction as efficient transition metal‐based electrocatalysts still remains a challenge.…”