Ethanol Solution Plasma Loads Carbon Dots onto 2D HNb 3 O 8 for Enhanced Photocatalysis.

Layered metal oxoacids hold potential as photocatalysts due to their facile exfoliation to two-dimensional (2D) nanosheets with a large surface area and a short migration distance for photoexcited charge carriers. However, the utilization of electrons in photocatalytic processes is restricted by the competitive trapping of electrons by metal ions. In this work, we attempt to improve the utilization of photogenerated electrons over exfoliated HNb 3 O 8 nanosheets by solution plasma activation. On dispersing exfoliated HNb 3 O 8 nanosheets in ethanol solution plasma, the defects in HNb 3 O 8 can be engineered, and carbon dots (CDs) can be anchored on the surface of HNb 3 O 8 nanosheets in situ. In comparison with pristine HNb 3 O 8 nanosheets, the rate of photocatalytic hydrogen evolution can be increased by 317.7 times over the HNb 3 O 8 /C heterojunction, and the apparent quantum efficiency of hydrogen production can be as high as 5.05%. The reason for the high photocatalytic performance is explored by the comparison of activation between plasma-in-ethanol and plasma-in-water, which reveals that CD anchoring and defect engineering indeed promote charge separation and hence lead to enhanced photocatalytic activity. This work provides an alternative approach to synthesize CDs and activate 2D-layered compounds with MO 6 (M = Nb, Ti, and W) octahedral building blocks in the host layer for enhanced photocatalytic evolution of hydrogen.