Atomic-layered V2C MXene containing bismuth elements: 2D/0D and 2D/2D nanoarchitectonics for hydrogen evolution and nitrogen reduction reaction

The exploitation of two-dimensional (2D) vanadium carbide (V2CTx, denoted as V2C) in electrocatalytic hydrogen evolution reaction (HER) and nitrogen reduction reaction (NRR) is still in the stage of theoretical study with limited experimental exploration. Here, we present the experimental studies of V2C MXene-based materials containing two different bismuth compounds to confirm the possibility of using V2C as a potential electrocatalyst for HER and NRR. In this context, for the first time, we employed two different methods to synthesize 2D/0D and 2D/2D nanostructures. The 2D/2D V2C/BVO consisted of BiVO4 (denoted BVO) nanosheets wrapped in layers of V2C which were synthesized by a facile hydrothermal method, whereas the 2D/0D V2C/Bi consisted of spherical particles of Bi (Bi NPs) anchored on V2C MXenes using the solid-state annealing method. The resultant V2C/BVO catalyst was proven to be beneficial for HER in 0.5 M H2SO4 compared to pristine V2C. We demonstrated that the 2D/2D V2C/BVO structure can favor the higher specific surface area, exposure of more accessible catalytic active sites, and promote electron transfer which can be responsible for optimizing the HER activity. Moreover, V2C/BVO has superior stability in an acidic environment. Whilst we observed that the 2D/0D V2C/Bi could be highly efficient for electrocatalytic NRR purposes. Our results show that the ammonia (NH3) production and faradaic efficiency (FE) of V2C/Bi can reach 88.6 μg h-1 cm-2 and 8% at -0.5 V vs. RHE, respectively. Also V2C/Bi exhibited excellent long-term stability. These achievements present a high performance in terms of the highest generated NH3 compared to recent investigations of MXenes-based electrocatalysts. Such excellent NRR of V2C/Bi activity can be attributed to the effective suppression of HER which is the main competitive reaction of the NRR.