Atomic-layered V 2 C 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 (V 2 CT x , denoted as V 2 C) 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 V 2 C MXene-based materials containing two different bismuth compounds to confirm the possibility of using V 2 C 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 V 2 C/BVO consisted of BiVO 4 (denoted BVO) nanosheets wrapped in layers of V 2 C which were synthesized by a facile hydrothermal method, whereas the 2D/0D V 2 C/Bi consisted of spherical particles of Bi (Bi NPs) anchored on V 2 C MXenes using the solid-state annealing method. The resultant V 2 C/BVO catalyst was proven to be beneficial for HER in 0.5 M H 2 SO 4 compared to pristine V 2 C. We demonstrated that the 2D/2D V 2 C/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, V 2 C/BVO has superior stability in an acidic environment. Whilst we observed that the 2D/0D V 2 C/Bi could be highly efficient for electrocatalytic NRR purposes. Our results show that the ammonia (NH 3 ) production and faradaic efficiency (FE) of V 2 C/Bi can reach 88.6 μg h -1 cm -2 and 8% at -0.5 V vs. RHE, respectively. Also V 2 C/Bi exhibited excellent long-term stability. These achievements present a high performance in terms of the highest generated NH 3 compared to recent investigations of MXenes-based electrocatalysts. Such excellent NRR of V 2 C/Bi activity can be attributed to the effective suppression of HER which is the main competitive reaction of the NRR.