Transforming Nickel Hydroxide into 3D Prussian Blue Analogue Array to Obtain Ni2P/Fe2P for Efficient Hydrogen Evolution Reaction

• Published in: Advanced energy materials 2018-07, Vol.8 (21), p.n/a
• Main Authors: Ge, Yuancai, Dong, Pei, Craig, Steven R., Ajayan, Pulickel M., Ye, Mingxin, Shen, Jianfeng
• Format: Article
• Language: English
• Subjects: Acids; Arrays; Current density; ferrum phosphide; Foils; Hydrogen evolution reactions; Iron; Metal-organic frameworks; Morphology; nanoarrays; Nickel; Nickel compounds; nickel phosphide; Pigments; Plates (structural members); Potassium ferricyanide; Precursors; Prussian blue analogues; Synthesis; Titanium
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201800484

For the first time, a 3D Prussian blue analogue (PBA) with well‐defined spatial organization is fabricated by using a nickel hydroxide array as a precursor. The nickel hydroxide arrays are synthesized in titanium foil and reacted with K3[Fe(CN)6]. The plate‐like morphology of the nickel hydroxide is perfectly preserved and combined with abundant PBA nanocubes. After phosphidation at 350 °C, the obtained sample demonstrated excellent hydrogen evolution reaction (HER) activity in both acid and alkaline solutions to reach a current density of 10 mA cm−2 with an overpotential of only 70 and 121 mV, respectively. With an overpotential of 266 mV, it can reach a larger current density of 500 mA cm−2 in acid. The efficient HER activity of the obtained sample is mainly ascribed to its structural advantage with various active metal sites derived from the nickel hydroxide and PBA precursor. In addition, long‐term stability measurements have verified the good performance of the obtained sample in acid and alkaline solutions. An increment of overpotential of only 8 and 9 mV is observed, in the acid and alkaline solutions respectively. Beyond these assets, it is supposed that the strategy to synthesize 3D PBA arrays from nickel hydroxide can be extended to other metal–organic frameworks arrays for more electrochemical applications. For the first time, Prussian blue analogue (PBA) arrays are fabricated which inherit the crystal structure of PBA and morphology of nickel hydroxide. After phosphidation, the 3D PBA demonstrates superb activity toward the hydrogen evolution reaction in both acid and alkaline solutions, which can reach a remarkable current density of 500 mA cm−2 with overpotentials of only 266 and 300 mV, respectively.