Construction of Defect‐Rich Ni‐Fe‐Doped K_0.23MnO₂ Cubic Nanoflowers via Etching Prussian Blue Analogue for Efficient Overall Water Splitting

Abstract

Designing elaborate nanostructures and engineering defects have been promising approaches to fabricate cost‐efficient electrocatalysts toward overall water splitting. In this work, a controllable Prussian‐blue‐analogue‐sacrificed strategy followed by an annealing process to harvest defect‐rich Ni‐Fe‐doped K0.23MnO2 cubic nanoflowers (Ni‐Fe‐K0.23MnO2 CNFs‐300) as highly active bifunctional catalysts for oxygen and hydrogen evolution reactions (OER and HER) is reported. Benefiting from many merits, including unique morphology, abundant defects, and doping effect, Ni‐Fe‐K0.23MnO2 CNFs‐300 shows the best electrocatalytic performances among currently reported Mn oxide‐based electrocatalysts. This catalyst affords low overpotentials of 270 (320) mV at 10 (100) mA cm−2 for OER with a small Tafel slope of 42.3 mV dec−1, while requiring overpotentials of 116 and 243 mV to attain 10 and 100 mA cm−2 for HER respectively. Moreover, Ni‐Fe‐K0.23MnO2 CNFs‐300 applied to overall water splitting exhibits a low cell voltage of 1.62 V at 10 mA cm−2 and excellent durability, even superior to the Pt/C||IrO2 cell at large current density. Density functional theory calculations further confirm that doping Ni and Fe into the crystal lattice of δ‐MnO2 can not only reinforce the conductivity but also reduces the adsorption free‐energy barriers on the active sites during OER and HER.

Waste to wealth: Defect-rich Ni-incorporated spent LiFePO4 for efficient oxygen evolution reaction

“…As shown in Fig. 3f, the during the OER [21,42,43]. To rationalize the improved water oxidation performance of the evolved Ni-LiFePO 4 , density functional theory (DFT) calculations were conducted at Fe sites from the corresponding models of LiFePO 4 (Fig.…”

“…A previous study suggests that doping exotic transition metals to create active reaction centers can be used as a general principle for the synthesis of catalysts with improved catalytic performance [21][22][23]. Herein, we proposed a facile strategy to modify and regenerate spent battery cathode material into an efficient catalyst, achieving a successful functional shift from battery electrode to electrocatalyst.…”

Construction of Petal-Like Ag NWs@NiCoP with Three-Dimensional Core-Shell Structure for Overall Water Splitting

“…All the electrochemical measurements were performed using a CHI760E workstation (Chenhua Corp., Shanghai, China) in 1.0 M KOH (pH = 13.9). Electrodes were prepared using the same methods previously mentioned in the literature [ 29 ]. The loading of catalysts was controlled to be about 2 mg·cm −2 .…”

Structural Design Strategy and Active Site Regulation of High‐Efficient Bifunctional Oxygen Reaction Electrocatalysts for Zn–Air Battery

“…Furthermore, the introduction of surface functional melamine sponge (MS) could promote the nucleation and growth of ZIF-67 for formation of graft ZIF-67 structures on the surface of MS (Figure 3d), improving the oxygen reaction activity. [36] In addition to MOF derivatives, layered double hydroxides (LDHs), [37] Prussian blue analogs (PBAs), [38] metal sulfides, and oxides [39] have also been used to prepare bifunctional ORR/ OER catalysts with hierarchical porous structure. Cho et al used a two-step method to derive Ni 6/7 Fe 1/7 -OH-6 catalyst from metal sulfide.…”