Polyoxometalates (POMs) are highly versatile materials if paired with various conducting supports. We here present a new prospective approach for obtaining advanced electrocatalytic systems via POMs (1 and 2) nanostructured… Click to show full abstract
Polyoxometalates (POMs) are highly versatile materials if paired with various conducting supports. We here present a new prospective approach for obtaining advanced electrocatalytic systems via POMs (1 and 2) nanostructured on Ni foam (NF) to give bimetallic nanohybrid composite materials M0.4Ni0.6/WO3 (M = Rh (3) or Ir (4)). By this pathway, two rare isopolyoctatungstate-based organometallic clusters [Hx(MCp*)4W8O32]·yH2O (in 1, M = Rh, x = 8, y = 23; in 2, M = Ir, x = 4, y = 17.33) have been synthesized via one-pot reactions using [Cp*MCl2]2 (Cp* = pentamethylcyclopentadienyl, M = Rh or Ir) and Na2WO4·2H2O in basic conditions. Compounds 1 and 2 were successfully nanostructured on the surface of commercially available NF and were thermally reduced to M0.4Ni0.6/WO3 (M = Rh (3) or Ir (4)) after annealing at 400 °C for 8 h in a 15% H2/N2 atmosphere. Electrodes modified with the POMs 3 and 4 exhibited remarkable HER activities in a 1 M KOH solution and achieved a current density of 10 mA cm-2 at low overpotentials of about 67 and 35 mV versus RHE, with Tafel slopes of 56 and 34 mV dec-1, respectively.
               
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