Porous NiFe-Oxide Nanocubes as Bifunctional Electrocatalysts for Efficient Water-Splitting

Abstract

Electrocatalytic water-splitting, a combination of oxygen and hydrogen evolution reactions (OER and HER), is highly attractive in clean energy technologies, especially for high-purity hydrogen production, whereas developing stable, earth-abundant, bifunctional catalysts has continued to pose major challenges. Herein, a mesoporous NiFe-oxide nanocube (NiFe-NC) system is developed from a NiFe Prussian blue analog metal-organic framework as an efficient bifunctional catalyst for overall water-splitting. The NiFe-NCs with ∼200 nm side length have a Ni/Fe molar ratio of 3:2 and is a composite of NiO and α/γ-FeO. The NCs demonstrate overpotentials of 271 and 197 mV for OER and HER, respectively, in 1 M KOH at 10 mA cm, which outperform those of 339 and 347 mV for the spherical NiFe-oxide nanoparticles having a similar composition. The electrolyzer constructed using NiFe-NCs requires an impressive cell voltage of 1.67 V to deliver a current density of 10 mA cm. Along with a mesoporous structure with a broad pore size distribution, the NiFe-NCs demonstrate the qualities of a desired corrosion-resistant water-splitting catalyst with long-term stability. The exposure of active sites at the edges and vertices of the NCs was validated to play a crucial role in their overall catalytic performance.

Ultralow FeIII Ion Doping Triggered Generation of Ni3S2 Ultrathin Nanosheet for Enhanced Oxygen Evolution Reaction

“…Linear sweep voltammetry (LSV) measurements were carried out with 95 % iR ‐compensations at 1 mV s −1 . The linear portions of the Tafel plots were derived from the LSV curves according to the Tafel equation: η = b log ( j )+a, where j represents the current density and b is the Tafel slope . The ECSA of electrodes were estimated by double layer capacitance measurements .…”

“…The linear portions of the Tafel plots were derived from the LSV curves according to the Tafel equation: η = blog (j) + a, where j represents the current density and b is the Tafel slope. [13] The ECSA of electrodes were estimated by double layer capacitance measurements. [31] To measure electrochemical capacitance, a series of CVs were performed across À 0.05 V~0.05 V of the open-circuit potential at scan rates of 5, 10, 25, 50, 100 and 200 mV s À 1 .…”

“…[7][8][9] Thus, sufficient efforts have been tried to develop efficient, durable and low-cost transitional metal-based OER catalysts to replace Ir-and Ru-based noble materials, which are unfit for large-scale industrial applications owing to their scarcity and high cost. [10,11] Recently, transitional metal-based oxide, [12][13][14] hydroxide, [15,16] chalcogenides, [17][18][19][20][21][22] selenide, [23,24] and phosphide [25][26][27][28] based on VIII group 3d metals (Fe, Co, and Ni) provide a promising OER activity in alkaline media. Among these materials, Ni-based sulfides have received intensively focus due to their favorable electrocatalytic performance toward water splitting and among them, Ni 3 S 2 is frequently used for electrochemical water splitting.…”

Highly Active Ternary Nickel–Iron oxide as Bifunctional Catalyst for Electrochemical Water Splitting

“…Likewise, Bhattacharyya et al. reported mesoporous NiFe‐oxide nanocubes as an efficient material for overall water‐splitting . The method follows a crystallization process of 7 days to form NiFe Prussian blue analog crystal which was further calcined to form NiFe 2 O 4 nanocubes.…”

“…[53] Likewise, Bhattacharyya et al reported mesoporous NiFe-oxide nanocubes as an efficient material for overall water-splitting. [54] The method follows a crystallization process of 7 days to form NiFe Prussian blue analog crystal which was further calcined to form NiFe 2 O 4 nanocubes. The nanocubes demonstrated excellent activity with overpotentials of 271 and 197 mV for OER and HER, respectively, in 1 M KOH at 10 mA cm À 2 .…”