High efficiency photocatalytic hydrogen production over ternary Cu/TiO2@Ti3C2Tx enabled by low-work-function 2D titanium carbide

Abstract

Abstract It is of prime importance to harness the transfer and flow of photogenerated electrons and holes to elongate the lifetimes of charge carriers and enhance the activity of semiconductor photocatalyst, which can be achieved by hybridizing the photocatalyst with appropriate cocatalysts with right electronic properties and placement. Herein, MXenes, a young family of two-dimensional transition metal carbides, are exploited as a hole mediator to enhance the photocatalytic activity of TiO 2 . We grow TiO 2 sheets exposing (001) surfaces on layered Ti 3 C 2 T x , and then photodeposited Cu 2 O nanodots on TiO 2 . We experimentally prove that the Ti 3 C 2 T x MXene from the wet HF etching method behaves as a low work function material ( ϕ = 3.4 eV). Thanks to this unique electronic property, the photogenerated electrons on TiO 2 hybridized with Ti 3 C 2 T x accumulate and tunnel to Cu 2 O to reduce it to elemental Cu as a reduction cocatalyst. The resulting Cu/TiO 2 @Ti 3 C 2 T x photocatalyst efficiently split water to produce hydrogen at 860 μmol g −1 h −1 . The results presented here demonstrate the promise of MXene materials in photocatalytic solar energy utilization. The insight into the electronic property of MXene sheds light on the new approach to the rational design of high-efficiency photocatalysts composed of MXenes.