Stepwise Reduction and In Situ Loading of Core-Shelled Pt@Cu Nanocrystals on TiO2-NTs for Highly Active Hydrogen Evolution

A flexible and mild fabricating protocol, i.e., stepwise reduction and in situ loading route, is proposed to modulate ordered growing and dispersive depositing of Pt@Cu bimetal layered nanostructure on titanium dioxide nanotubes (TiO2-NTs) via reasonably regulating addition sequence and dosage for the reactants and additives. Comprehensive characterizations demonstrate that most of the Cu core-Pt shell nanocrystals with a mean size of 10 nm evenly disperse on the surface of TiO2-NTs, and a small number of nanocrystals permeate into the nanotubes. In comparison to TiO2-NTs, the specific surface area declines after loading bimetals, with the pore size distribution shifting from micropores to mesopores. The catalytic activity of the Pt@Cu(x)/TiO2 for hydrolytic hydrogen evolution presents an increasing tendency as the bimetal loadings rise, each surpassing that of the bare bimetal nanocrystals. The H-2 generating rate gradually rises with temperature increment. The AB hydrolysis catalyzed by Pt@Cu(9%)/TiO2 at the given temperatures (293-313 K) is affirmed as a first-order reaction, with apparent activation energy of 28.43 kJ mol(-1) and TOF value of 107.27 min(-1). The catalyst Pt@Cu(9%)/TiO2 unfolds exceptionally high stability, remaining 91% initial catalytic activity after five cycling use.