In situ anchoring of Co9S8 nanoparticles on N and S co-doped porous carbon tube as bifunctional oxygen electrocatalysts

Abstract

The development of cost-effective yet highly active and robust bifunctional electrocatalyst for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) has been at the forefront of research into regenerative fuel cells and metal-air batteries. Here we report Co 9 S 8 nanoparticles grown in situ on nitrogen-and sulfur-doped porous carbon (Co 9 S 8 /NSPC) as a bifunctional catalyst for OER and ORR using poly(2-aminothiazole) as a novel all-in-one multifunctional precursor. Unexpectedly, Co 9 S 8 /NSPC exhibits a low OER overpotential, positive ORR half-wave potential, small potential gap and high durability, thus making it one of the best bifunctional OER and ORR catalysts. This may be attributed to the heteroatom doping, porous structure and synergistic effects of Co 9 S 8 and NSPC, as confirmed by density functional theory calculations. More importantly, as a proof-of-concept application, the air electrode with Co 9 S 8 /NSPC9-45 endows the Zn-air battery with a low discharge/charge overpotential and good cycling stability.

Co9S8 Nanoparticles‐Embedded N/S‐Codoped Carbon Nanofibers Derived from Metal–Organic Framework‐Wrapped CdS Nanowires for Efficient Oxygen Evolution Reaction

“…The peaks at 161.5 and 162.3 eV are attributed to the S 2p 3/2 and S 2p 1/2 of CoS, respectively, basically arising from Co 9 S 8 . While the peaks at 163.5 and 165.1 eV are attributed to CSC, and the peak at 167.9 eV can be assigned to SO 4 2− . The presence of CSC conforms that S atoms were well doped into carbon matrix besides forming the Co 9 S 8 nanoparticles.…”

“…It is found that Co 9 S 8 /NSCNFs‐850 exhibits superior OER activity with the lowest overpotential of 302 mV to afford 10 mA cm −2 , which is smaller than those of Co 9 S 8 /NSCNFs‐950 (314 mV) and Co 9 S 8 /NSCNFs‐750 (333 mV), and even 30 mV smaller than that of commercial RuO 2 catalyst. Notably, this overpotential is smaller than those of most reported cobalt sulfide‐based OER catalysts, such as Co 9 S 8 /NSPC9‐45 (310 mV), Co@Co 9 S 8 ‐180 (350 mV), and CoS 2 (400)/N, S‐GO (380 mV), and more advantageous compared with highly active non‐noble‐metal OER catalysts (Table S1, Supporting Information). Additionally, Co 9 S 8 /NSCNFs‐850 also reveals a lower onset potential of 1.48 V versus RHE, further indicating the excellent OER activity.…”

“…The N 1s spectrum could be deconvoluted into three peaks, which are pyridinic N (398.6 eV), pyrrolic N (400.1 eV), and graphitic N (401.1 eV) (Figure e) . In the case of the high‐resolution XPS spectrum of C 1s shown in Figure f, four peaks at 284.0, 284.7, 285.2, and 286.2 eV can be obtained ascribed to CSC, CCC, CO, and CN species, respectively, suggesting the successful incorporation of N and S atoms into the carbon structures . Both of the Co 9 S 8 and N/S‐codoped carbon species are believed to be promoting for the performance of OER.…”

“…Generally, growing or supporting the nanoparticles on conductive carbon‐based substrates like graphene and carbon nanotubes is an effective approach to improve their electronic conductivity . Unfortunately, the cobalt chalcogenides nanoparticles tend to detach from the carbon substrates into large aggregation which prevents the exposure of the active sites . Hence, anchoring or embedding the active cobalt chalcogenides nanoparticles on/in heteroatom‐doped carbons can be a promising way to solve this problem .…”

Adsorption-energy-based activity descriptors for electrocatalysts in energy storage applications

“…water, dinitrogen, inactivated metal oxide) into high-value products (e.g. hydrogen, ammonia, activated cations and anions) [3,4]. Thus, electrocatalysis, in the broadest sense, dominates the electrochemical performance.…”