Hybrid n-type Sn1−xTaxO2 nanowalls bonded with graphene-like layers as high performance electrocatalysts for flexible energy conversion devices
We report here hybrid n-type Ta-doped SnO2 (Sn1−xTaxO2) nanowalls (as an electron-rich donor) bonded with graphene-like layers (Sn1−xTaxO2/C) as high performance electrocatalysts for flexible energy conversion devices. SnO2 possesses high electron mobility (125–250 cm2 V−1 S−1), and Ta doping is adopted to increase the electron concentration to further improve the conductivity of the SnO2 film to allow its use as a catalyst support. Our first-principles calculations reveal that the increased electrical conductance is mainly attributed to the increased intrinsic doping effect caused by the substitution of Sn by Ta. The Ta-doped SnO2 not only acts a well conductive support for the close coated graphene-like carbon layers but also pushes electrons to the carbon electrocatalyst to enhance its catalytic performance. Advanced features of these nanowall films include not only a high specific surface area, and good adhesion to substrates, but also flexibility. One application as a counter electrode in fully flexible dye-sensitized solar cells (DSSCs) shows that the optimal power conversion efficiency (PCE) of fully flexible DSSCs is 8.38% under AM1.5G illumination (100 mW cm−2), which is one of the highest PCEs for fully flexible DSSCs.