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Mastery over the structure of materials at nanoscale can effectively tailor and control their catalytic properties, enabling enhancement in both activity and durability. We report a size-controlled synthesis of novel Pt-Cu hierarchical trigonal bipyramid nanoframes (HTBNFs). The obtained nanocrystals looked like a trigonal bipyramid on the whole, composed of similar ordered frame structural units. By varying the amount of KI involved in the reaction, HTBNFs with variable sizes from 110 to 250 nm could be obtained. In addition, the structure of HTBNFs could be preserved only in a limited range of the Pt/Cu feeding ratio. Relative to the commercial Pt/C, these Pt-Cu HTBNFs with different Pt/Cu ratio exhibited enhanced electrocatalytic activity toward formic acid oxidation reaction as much as 5.5 times in specific activity and 2.1 times in mass activity. The excellent electrocatalytic activity and better durability are due to the unique structure of HTBNFs and probably synergetic effects between Pt and Cu.

In this work, we clearly demonstrate for the first time the use of transition-metal phosphides to set up a new cathodic analysis platform for sensitive and selective electrochemical nonenzymatic detection of H2O2. With the help of a facile topotactic conversion method, the noble metal-free electrocatalyst of copper(I) phosphide nanowires on three-dimensional porous copper foam (Cu3P NWs/CF) is fabricated with electrochemical anodized Cu(OH)2 NWs as precursor. The Cu3P NWs/CF-based sensor presents excellent electrocatalytic activity for H2O2 reduction with a detection limit of 2 nM, the lowest detection limit achieved by noble-metal free electrocatalyst, which guarantees the possibility of sensitive and reliable detection of H2O2 release from living tumorigenic cells, thus showing the potential application as a sensitive cancer cell detection probe.

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