Total Water Splitting Catalyzed by Co@Ir Core–Shell Nanoparticles Encapsulated in Nitrogen-Doped Porous Carbon Derived from Metal–Organic Frameworks

Abstract

Developing bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) toward overall water splitting with high efficiency and robust durability is highly desirable but very challenging. Herein, we report a highly efficient and robust bifunctional electrocatalyst for overall water splitting based on Co@Ir core–shell nanoparticles encapsulated in nitrogen-doped porous carbon derived from metal–organic frameworks. The series of Co@Ir/NC-x samples were prepared through a galvanic replacement of IrCl3 with Co/NC, which was obtained by calcination of zeolitic imidazolate framework 67 (ZIF-67). In the electrocatalytic characterizations toward OER and HER, Co@Ir/NC-10% exhibited the best performance among the series, with an overpotential of 280 mV at a current density of 10 mA cm–2 for OER, superior to the benchmark IrO2 catalyst, and an overpotential of −121 mV at a current density of 10 mA cm–2 for HER in 1 M KOH. Moreover, Co@Ir/NC-10% also demonstrated markedly higher long-term stability than IrO2 for OER and superior long-term durability than Pt/C for HER. Finally, the overall water splitting catalyzed by the series of composites was explored and visually observed.

Hierarchical iridium-based multimetallic alloy with double-core-shell architecture for efficient overall water splitting

“…Therefore, numerous scientific research efforts have been devoted to investigating and designing efficient noble metal nanocatalysts with high electrocatalytic activity, long-term stability and the use of non-noble metals. Alloying Ir with transition group metals [19,[24][25][26][27][28][29][30][31][32][33][34] is generally regarded as an effective strategy that not only substantially reduces the usage of Ir but also facilitates the catalytic activity and stability for water splitting by tuning the d-band structure and oxygen adsorption energy on the surface of Ir. Another strategy to optimize the overall catalytic activity is to tune the geometric shape of the nanocatalysts [18,[35][36][37][38][39][40][41][42].…”

A Morphologically Engineered Robust Bifunctional CuCo2O4 Nanosheet Catalyst for Highly Efficient Overall Water Splitting

“…Figure a shows the polarization curve of the fabricated bifunctional CCO nS || CCO nS nanocatalyst electrolyser. It reveals that the CCO nS || CCO nS bifunctional catalyst could provide 10 mA cm −2 current density to deliver the full‐cell voltage of 1.64 V, which is favorably comparable with various state‐of‐the‐art water‐based alkaline electrolysers (Figure b) . Although the NiFeMo(OOH) attained the lowest cell voltage of 1.45 V, its activity was decayed initially during stability and then this electrolyser maintained a voltage of 1.6 V throughout the bifunctional full‐cell stability.…”

NiFe Alloyed Nanoparticles Encapsulated in Nitrogen Doped Carbon Nanotubes for Bifunctional Electrocatalysis Toward Rechargeable Zn‐Air Batteries

“…Based on the Barrett-Emmett-Teller (BET) curves, the surface area of Ni 50 Fe 50 @N-CNTs was calculated as 204.03 m 2 g À 1 . [23] The representative TEM image of Ni 50 Fe 50 @N-CNTs is shown in Figure 1a, and it discloses that various particles with different sizes are predominantly encapsulated into the carbon nanotubes, and the further higher magnification TEM image of Ni 50 Fe 50 @N-CNTs in Figure 1b reveals that the particle exhibited an irregular spherical shape. From the HR-TEM image of Ni 50 Fe 50 @N-CNTs, the lattice spacing of 0.208 nm is in good accordance with the crystal plane of Ni 0.36 Fe 0.64 (111), suggesting the formation of NiFe alloys.…”