Fig. 4: DFT calculations of HER on several electrocatalysts. | NPG Asia Materials

Fig. 4: DFT calculations of HER on several electrocatalysts.

From: Tailoring the d-band center of N-doped carbon nanotube arrays with Co4N nanoparticles and single-atom Co for a superior hydrogen evolution reaction

Fig. 4

a Free-energy diagram of the HER on various Co and Co4N catalysts, b partial electronic density of states (PDOS) for the d orbital of bare Co, bare Co4N, Co@C, Co4N@C, Co@NC, and Co4N@NC. The dotted lines represent the Fermi level, and the d-band centers of Co atoms are provided with the colored font. Charge density differences of the N-doped carbon layer in the models of: c Co4N@C, d Co@NC, e Co@NC, and f Co4N@NC. In the structures of (c–f), Co, N, and C are marked in cyan, blue, and gray, respectively. In regard to the charge density differences, red and green represent charge accumulation and depletion, respectively. The isosurface cutoff is 0.005 electronsÅ−3. g Free-energy diagram of the HER at various single-atom Co sites of the Co4N@CoSA/N-CNT/CC electrocatalyst.

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