Investigation of mixed-metal (oxy)fluorides as a new class of water oxidation electrocatalysts

Abstract

The development of electrocatalysts for the oxygen evolution reaction (OER) is one of the principal challenges in the area of renewable energy research.

Electrochemical oxygen evolution reaction efficiently boosted by selective fluoridation of FeNi3 alloy/oxide hybrid

“…A three-dimensional porous architecture derived from Fe-Co Prussian blue analog by low-temperature fluoridation etching can drive 10 mA cm −2 at 250 mV [31] ; similar case was also reported on the Ni 2 P, that can afford an overpotential of 283 mV to drive 10 mA cm −2 , about 60 mV less loaded on an inert glassy carbon electrode after controlled fluoridation process [32] . Mixed-metal (oxy)fluorides as a new class for water oxidation electrocatalysts were also confirmed just recently [33] , where an excellent activity with the overpotential as low as 270 mV for 10 mA cm −2 was found on CoFe oxyfluorides. As mentioned above, the structure transformation from the pre-catalyst to the real catalyst of metal (oxy)hydroxide was highly desired for the OER catalysts.…”

Mechanochemically Synthetized PAN-Based Co-N-Doped Carbon Materials as Electrocatalyst for Oxygen Evolution Reaction

“…These findings imply that the Co-doped PAN-N materials promoted ultrahigh OER kinetics; in general, the low Co content samples were the ones with the lower Tafel slopes. These low Tafel slope values indicate that the second reaction of the OER mechanism in alkaline media was rate-determining [ 56 ]. The low Tafel slope also indicates a strong adsorption of surface intermediates in the primary step, hampering the following step which became rate limiting [ 57 ].…”

Halide-Doping Effect of Strontium Cobalt Oxide Electrocatalyst and the Induced Activity for Oxygen Evolution in an Alkaline Solution

“…Figure 4 shows the deconvoluted core spectra analysis of the O 1s peak for the Sr 2 CoO 3 F, Sr 2 CoO 3 Cl, Sr 2 CoO 3 Br, and parent Sr 2 CoO 4 while Table 2 reports the deconvoluted O 1s peaks binding energy and oxygen bonding ratio values of the studied oxyhalide catalysts. The O 1s fitted core spectra in Figure 4 reveal the presence of a peak at lower binding energy (peak 1) that can be assigned to the O 2− anion of the lattice oxygen and the peak in the middle is related to the surface O 1− ions (peak 2), while the peak at higher binding energy (peak 3) is due to the chemically adsorbed oxygen species (O chem ) at the surface [47,48]. However, the O 1s spectrum of the parent Sr 2 CoO 4 catalyst (Figure 4d) can only be fitted by two peaks that are assigned for O 2− anion (peak 1) and O 1− /O chem (peak 2), possibly because of a small amount of chemically adsorbed oxygen species.…”

“…However, the O 1s spectrum of the parent Sr 2 CoO 4 catalyst (Figure 4d) can only be fitted by two peaks that are assigned for O 2− anion (peak 1) and O 1− /O chem (peak 2), possibly because of a small amount of chemically adsorbed oxygen species. From the data in Table 2 and upon the incorporation of halide ions, the overall peaks' binding energy is shifted to lower values in the order F − > Cl − > Br − which indicates a weaker Co-O bonding due to withdrawn the electron density away from the Co-atom, consequently enhances the lattice oxygen (O 2− ) reactivity and reduces the activation energy required for O 2− activation [47][48][49]…”