Effectively engineering in situ coupled cobalt-cobalt phosphide nanoparticles with nitrogen-doped carbon materials for advanced bifunctional oxygen electrocatalysts in rechargeable Zn-air batteries

Facile Synthesis of Co2P Nanoparticles Embedded in N- and P-Doped Mesoporous Carbon Composite as an Efficient Electrocatalyst for Oxygen Evolution Reaction

“…As the spontaneous electrochemical oxidation/dephosphorization proceeds, the signals of the P 2p 3/2 peak at 129.6 eV and the Co 2p 3/2 peak at 778.1 eV attributed to Co 2 P are barely discernible above the noise level, validating the occurrence of the electrochemical oxidation of cobalt phosphides into Co (oxy)­hydroxides at the surface. , This is further verified by the O 1s XPS spectrum (Figure f). A new peak at 529.7 eV corresponds to Co–O bonds in both Co 2 P@NPC-10 and Co 2 P@NPC-20, which are derived from the formation of Co-based surface (oxy)­hydroxides during the OER process. − Furthermore, the fraction of Co–O bonds gradually increases as the CV cycles increase, clearly indicating that more and more Co–O bonds are generated, which agrees well with the Co 2p 3/2 XPS results. Another new peak located at 535.4 eV is assigned to the H–O–H bond of chemisorbed water. , Moreover, Co 2 P@NPC-20 exhibits the increased oxidation state of Co species compared with Co 2 P@NPC-10.…”

“…As expected, the related Tafel plots can provide further evidence of this in Figure g. Co 2 P@NPC-20 presents a smaller Tafel slope than RuO 2 , indicating its fast OER kinetics. , The Faradaic efficiency for Co 2 P@NPC-20 is determined as nearly 100% (Figure S3), which indicates that almost all of the current was in charge of OER. , Furthermore, the chronopotentiometry (CP) curve was recorded at 10 mA cm –2 for 20 h, as shown in Figure h. It is observed that the operation potential of Co 2 P@NPC continues to decrease at the beginning and after 5 h slowly increases but is still lower than the initial value after 20 h. The pristine improvement of OER activity corresponds to the gradual formation of reconstructed Co (oxy)­hydroxides, as discussed above.…”

“…The synthesis of Co 2 P@NPC was realized through a one-step approach by in situ phosphating and carbonization process. 30 During the pyrolysis process, Co 2 P nanoparticles were formed by the reaction between Co(ac) 2 and (NH 4 ) 2 HPO 4 , coupled with the formation of N, P-codoped carbonaceous materials, which resulted from the pyrolysis of a biomass mixture including melamine and glucose and phosphate. The morphology of the Co 2 P@NPC composite was first investigated by scanning electron microscopy (SEM).…”

Tailored Crafting of CoP/Ni2P Nanoparticles Coupled with N-Doped Nanoporous Carbon to Enable Efficient Hydrogen and Oxygen Evolution

“…For the Co 2p 3/2 spectrum of CoP(Ni 2 P)/NC (Figure 3c), the peak at 778.24 eV belongs to metallic Co in CoP, while the peaks at 781.16, 782.62, and 786.29 eV can be assigned to Co 3+ , Co 2+ , and satellites, respectively. 30 In the high-resolution Ni 2p 3/2 region (Figure 3d), the distinct peak at 853.02 eV is attributable to metallic Ni in Ni 2 P. 10,31 Additionally, the 2p 3/2 peaks of Ni 2+ and satellites are located at 856.44 and 860.71 eV, respectively. The above results indicate that the metal phosphides were partially oxidized when exposed to air.…”

“…Figure f is the P 2p XPS spectrum. The peaks at 128.89 and 130 eV are attributed to P 2p 3/2 and P 2p 1/2 , respectively, corresponding to P in CoP­(Ni 2 P). The additional peak at 133.74 eV resulted from the P–O band, indicating the surface oxidation of TMPs.…”