Graphene-Decorated Boron–Carbon–Nitride-Based Metal-Free Catalysts for an Enhanced Hydrogen Evolution Reaction

Abstract

The hydrogen evolution reaction (HER) is an emerging renewable energy source to derive clean, efficient, and high-energy-density hydrogen fuel from electrochemical water splitting mostly by using traditional noble-metal-based catalysts. However, their scarcity has led to the emergence of carbon-based materials which are exceptionally promising alternatives for the HER. Herein, graphene capsules-decorated boron–carbon–nitride sheets are developed by pyrolyzing a mixture of pyridine borane and custom-made GCs. The 3D hollow GCs effectively increase the surface area to supplement more exposed active sites for the hydrogen adsorption/desorption reaction. The carbon-rich ternary hybrid structure favors adjusting the electrical conductivity, which provides better HER catalytic performances (overpotential of 333 mV at 10 mA cm–2) in acidic conditions. The long-term stability for 24 h and the simplest designing technique propose an effective metal-free electrocatalyst for commercial applications in the renewable energy field.

Intermolecular Electron Transfer in Electrochemically Exfoliated BCN-Cu Nanosheet Electrocatalysts for Efficient Hydrogen Evolution

“…While the high intensity band at 3435 cm –1 is characteristic of the N–H stretching vibration, the bands at 2921.7 and 2852.9 cm –1 are ascribed to C–H stretching. The bands characteristic of the N–H and C–H bending were also recorded at 1628.9 and 1378.2 cm –1 , respectively . The band around 1500 cm –1 can be assigned to C–O axial deformation .…”

“…8 eV, respectively. 44,60 The Cu 2p spectrum (Figure 4e) exhibited two peaks at 933 and 952.9 eV corresponding to Cu 0 , along with weak signals at 934.8 and 954.8 eV assigned to Cu 2+ , which is also confirmed by the satellite peaks at 940 and 944.5 eV. 60,61 The catalytic activity of the fabricated composites for hydrogen evolution reaction (HER) was investigated in a three-electrode setup.…”

“…The bands characteristic of the N−H and C−H bending were also recorded at 1628.9 and 1378.2 cm −1 , respectively. 44 The band around 1500 cm −1 can be assigned to C−O axial deformation. 45 Note that it is shifted to ∼1627 cm −1 , which may confirm the formation of a copper complex, as the positions of C�O and NH 2 may overlap.…”

“…46 The band at 1119.7 cm −1 confirms the formation of the C−B bond, while both bands at 1050 and 1250 cm −1 are attributed to C−N stretching. 44,47 To further confirm the formation of BCN nanosheets, Raman measurements were conducted, see Figure 3b. The recorded Raman spectrum demonstrated the distinctive peaks at around 1372 and 1600 cm −1 related to the D and G bands, respectively, along with two weak signals at 2686 and 2920 cm −1 characteristic of the 2D band, in agreement with the reported Raman spectrum of BCN nanosheets.…”

“…49 Moreover, the presence of a weak 2D band signifies the presence of a few layers of BCN nanosheets. 44,49,50 While the G band represents the stretching of all sp 2 bonds (C−C, N−C, B−C, and B−N), the D band is related to the sp 3 defects. 51 The I d /I g ratio was calculated and found to be 0.95, 0.85, 1, and 0.87 for the as-prepared BCN nanosheets, BCN nanosheets after chronopotentiometry (CP), as-prepared 0.125 Cu-BCN nanosheets, and 0.125 Cu-BCN nanosheets after CP, respectively.…”