Exceptional performance of hierarchical Ni–Fe oxyhydroxide@NiFe alloy nanowire array electrocatalysts for large current density water splitting

Abstract

Exceptionally high OER & HER performances were achieved by rationally designing the electrode structure of non-noble NiFe materials.

Core–Shell Structured NiFeSn@NiFe (Oxy)Hydroxide Nanospheres from an Electrochemical Strategy for Electrocatalytic Oxygen Evolution Reaction

“…Thus, introducing iron into NiSn would lead the XRD patterns to shift to lower angles, which indicates that the atom of iron has been incorporated into the structure of NiSn. [ 52–54 ] The XRD pattern of NiFe 0.5 shows two main peaks, which might include two kinds of Ni‐Fe alloys (Figure S10b, Supporting Information). The peak at 44.6° is indexed to Kamacite (JCPDS No.…”

“…Zero‐valent tin could also be found at 485.1 eV in the narrow scan spectrum of Sn 3d (Figure S12b, Supporting Information). Unfortunately, the Sn 3p binding energy region and the Ni LMM Auger peak overlap with the Fe 2p binding energy region under an Al electron source (Figure S12a, Supporting Information), [ 38,53,55,57–59 ] and thus the XPS analysis of Fe is seriously interfered with, as shown in Figure 3c. The resulted broad peak could be divided into two peaks at 714.3 and 716.7 eV, which belong to Ni LMM Auger peak and the Sn 3p binding energy region, respectively.…”

“…The resulted broad peak could be divided into two peaks at 714.3 and 716.7 eV, which belong to Ni LMM Auger peak and the Sn 3p binding energy region, respectively. [ 53,58 ] However, metallic iron is successfully identified by the peaks at 707.8 and 720.6 eV in the Fe 2p narrow scan spectrum. [ 52–54 ] The two peaks at 710.8 and 724.2 e V represent the iron oxide.…”

“…[ 53,58 ] However, metallic iron is successfully identified by the peaks at 707.8 and 720.6 eV in the Fe 2p narrow scan spectrum. [ 52–54 ] The two peaks at 710.8 and 724.2 e V represent the iron oxide. In sharp contrast, in the case of catalyst NiFe 0.5 without Sn, evident peaks of metallic iron at 707.3 and 720.6 eV are observed in the Fe 2p narrow scan spectrum of NiFe 0.5 , as shown in Figure 2d.…”

“…The electrochemical performance of NiFe 0.5 Sn exceeds all other alloys', which might be due to the most appropriate electronic structure modified by the Ni/Fe ratio. [ 53 ] For the purpose of surface reconstruction as well as selective etching of Sn, the alloy precatalysts would undergo a 2‐h galvanostatic anodization at a current density of 10 mA cm −2 (denoted as NiFe x Sn‐A). The electrocatalytic activity would be enhanced after anodization.…”