Plasma-modified graphitic C3N4@Cobalt hydroxide nanowires as a highly efficient electrocatalyst for oxygen evolution reaction

Investigation of Hydrogen and Oxygen Evolution on Cobalt-Nanoparticles-Supported Graphitic Carbon Nitride

“…The Co 2p 3/2 and Co 2p 1/2 peaks of the Co species at 779.9 and 795.5 eV, giving a spin-energy separation of 15.6 eV, is the characteristic of a Co 3 O 4 phase and matches well with the reported data [82][83][84]. Meanwhile, the deconvolution of the XPS spectrum of Co 2p 3/2 confirms the presence of different oxidation states of Co atoms as Co 3 O 4 (779.48 eV), and Co(II) oxides/hydroxides, including possible Co-N x structures, CoO, CoOOH, Co(OH) 2 (780.79 eV, 782.39 eV), with overlapping binding energies of different oxide and hydroxide forms [64,77]. In addition, the peak with a binding energy of 779.48 eV, attributed to the Co 3 O 4 species, clearly dominates over the other identified peaks, accounting for 40.22 at.%, thus confirming the successful synthesis of Co 3 O 4 giv-ing rise to the formation of a hybrid nanostructure with g-C 3 N 4 within the prepared Co 3 O 4 /gCN catalyst.…”

“…In Figure 6a, the highresolution XPS spectrum of Co 2p presents dominant peaks at 779.9 eV (2p 3/2 ) and 795.5 eV (2p 1/2 ), which are accompanied by shake-up satellite peaks at approximately 790.4 eV and 805.7 eV, respectively. The results show the occurrence of high-spin Co oxide species, indicating an admixture of Co 2+ and Co 3+ , the two cations present in the spinel structure of Co 3 O 4 [64,78,80,81]. The Co 2p 3/2 and Co 2p 1/2 peaks of the Co species at 779.9 and 795.5 eV, giving a spin-energy separation of 15.6 eV, is the characteristic of a Co 3 O 4 phase and matches well with the reported data [82][83][84].…”

“…Furthermore, the peak at 399.33 eV is prevailing, accounting for 42.74 at.%. This binding energy area covers the binding energy region required for the N−Co bond, which is difficult to distinguish [64,77,79] [78]. The binding energies of O 1s peaks at 531.26 eV and 532.53 are attributed to adsorbed oxygen species (water, oxygen, CO 2 ) [58,59,66,80].…”

“…The authors identified a controllable morphological effect to enhance the electrochemical performance and showed that optimized g−C 3 N 4 concentration plays a vital role in inducing the formation of hierarchical flower-like patterns, which not only prevents agglomeration but also provides a porous structure for enhanced gas diffusivity and charge transfer rates due to the synergistic carbon and nitrogen bonding with Co and NiS. Y. Shen et al [64] prepared g−C 3 N 4 @Co(OH) 2 nanowires using a plasma modification strategy. The developed catalyst was subjected to a 60 s plasma treatment, which generated more exposed active edge sites and increased the number of Co 3+ active sites for enhanced OER activity, displaying an overpotential of 329 mV.…”

“…Various strategies for synthesizing high-performance transition metal-modified g-C 3 N 4 -based catalysts, including annealing, microwave-assisted, and hydrothermal approaches, have been the subject of considerable research interest [62][63][64][65][66]. Each strategy has its own advantages and disadvantages.…”