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Metal-Phosphide-Containing Porous Carbons Derived from an Ionic-Polymer Framework and Applied as Highly Efficient Electrochemical Catalysts for Water Splitting
A novel phosphorus‐containing porous polymer is efficiently prepared from tris(4‐vinylphenyl)phosphane by radical polymerization, and it can be easily ionized to form an ionic porous polymer after treatment with hydrogen iodide. Upon ionic exchange, transition‐metal‐containing anions, such as tetrathiomolybdate (MoS4
2−) and hexacyanoferrate (Fe(CN)6
3−), are successfully loaded into the framework of the porous polymer to replace the original iodide anions, resulting in a polymer framework containing complex anions (termed HT‐Met, where Met = Mo or Fe). After pyrolysis under a hydrogen atmosphere, the HT‐Met materials are efficiently converted at a large scale to metal‐phosphide‐containing porous carbons (denoted as MetP@PC, where again Met = Mo or Fe). This approach provides a convenient pathway to the controlled preparation of metal‐phosphide‐loaded porous carbon composites. The MetP@PC composites exhibit superior electrocatalytic activity for the hydrogen evolution reaction (HER) under acidic conditions. In particular, MoP@PC with a low loading of 0.24 mg cm−2 (on a glass carbon electrode) affords an iR‐corrected (where i is current and R is resistance) current density of up to 10 mA cm−2 at 51 mV versus the reversible hydrogen electrode and a very low Tafel slope of 45 mV dec−1, in rotating disk measurements under saturated N2 conditions.
Metal‐phosphide‐loaded porous carbons (MetP@PCs) are prepared from a phosphorous‐containing ionic‐polymer framework. Unlike previously reported transition‐metal‐based electrocatalysts, the metal source for MetP@PCs are complex ions, rather than metal salts. Their performance in the electrochemical catalysis of the hydrogen evolution reaction is very promising, and the performance of the PC loaded with molybdenum phosphide is comparable with that of the commercial Pt/C catalyst.