Heteroatom Doped Amorphous/Crystalline Ruthenium Oxide Nanocages as a Remarkable Bifunctional Electrocatalyst for Overall Water Splitting

Abstract

Developing robust and highly active bifunctional electrocatalysts for overall water splitting is critical for efficient sustainable energy conversion. Herein, heteroatom‐doped amorphous/crystalline ruthenium oxide‐based hollow nanocages (M‐ZnRuOx (MCo, Ni, Fe)) through delicate control of composition and structure is reported. Among as‐synthesized M‐ZnRuOx nanocages, Co‐ZnRuOx nanocages deliver an ultralow overpotential of 17 mV at 10 mA cm−2 and a small Tafel slope of 21.61 mV dec−1 for hydrogen evolution reaction (HER), surpassing the commercial Pt/C catalyst, which benefits from the synergistic coupling effect between electron regulation induced by Co doping and amorphous/crystalline heterophase structure. Moreover, the incorporation of Co prevents Ru from over‐oxidation under oxygen evolution reaction (OER) operation, realizing the leap from a monofunctional to multifunctional electrocatalyst and then Co‐ZnRuOx nanocages exhibit remarkable OER catalytic activity as well as overall water splitting performance. Combining theory calculations with spectroscopy analysis reveal that Co is not only the optimal active site, increasing the number of exposed active sites while also boosting the long‐term durability of catalyst by modulating the electronic structure of Ru atoms. This work opens a considerable avenue to design highly active and durable Ru‐based electrocatalysts.

Accelerating Ru0/Ru4+ Adjacent Dual Sites Construction by Copper Switch for Efficient Alkaline Hydrogen Evolution

“…Figure 4c gives the corresponding Ru 3p 3/2 XPS curves of the RuO 2 sample; only one main peak located at 464.6 eV (Ru 4+ ) can be detected for cycles 1, 40, or 60. For cycles 80 or 100, the main peak moves to 462.7 eV; meanwhile, one new peak at 462.5 eV (Ru 0 ) appears, and the relative peak area ratios of Ru 0 to Ru 4+ are 0.75 and 0.8 (Table S5, Supporting Information) [38][39][40][41][42][43][44][45][46][47] for the samples of cycles 80 and 100, confirming that the activation of bare RuO 2 , that is, the surface metallic Ru site formation, needs at least 2 h. On a sample of Cu-RuO 2 , there are two obvious main peaks located at 462.5 and 465.2 eV in Ru 2p 3/2 XPS curves (Figure 4d), no binding energy shift can be detected, and the fitted peak area ratios of Ru 0 to Ru 4+ are all near 0.8 (Table S6, Supporting Information), further confirming that the Cu 2+ ions are the switch of RuO 2 reduction to Ru. Thus, the activation times of RuO 2 and Cu-RuO 2 are set at 150 and 7.5 min, respectively, and the Cu 2+ introduction will provide at least 95% energy savings.…”

“…f) EIS plots obtained under the applied bias of −0.1 V versus RHE of RuO 2 -AC and Cu-RuO 2 -AC. g) Comparison of the alkaline HER performance of Cu-RuO 2 -AC (red five-pointed star) with that of reported Ru-based catalysts [38][39][40][41][42][43][44][45][46][47]. h) Stability tests of Cu-RuO 2 -AC and RuO 2 -AC at their current density of 10 mA cm −2 .…”

Anchoring Ru nanoclusters to defect-rich polymeric carbon nitride as a bifunctional electrocatalyst for highly efficient overall water splitting

“…11,12 Nevertheless, from the economic perspective, Ru, which is much cheaper than Pt, is still more expensive than common transition metals (Fe, Co, Ni), impeding its large-scale application. 13,14 Consequently, reducing Ru loading and enhancing atomic utilization is crucial. When Ru species are reduced to nanoclusters (NCs) with near-complete exposure, the materials exhibit unique activity and stability properties unattainable by monometallic catalysts or their micro/nano counterparts.…”

Mesoporous Iron Family Element (Fe, Co, Ni) Molybdenum Disulfide/Carbon Nanohybrids for High-Performance Supercapacitors

“…59−62 Introducing metal heteroatoms in MoS 2 /C can effectively improve the structural stability of M x Mo 1−x S 2 /C. 26,27 Herein, we proposed to introduce iron family elements (Fe, Co, Ni) to MoS 2 by using SAB-15 without removing P123 as a template, and the transition metals were introduced into MoS 2 by a water bath method and calcined in a tube furnace to synthesize M x Mo 1−x S 2 /C, (M = Fe, Co, and Ni). Based on our investigations, the best performance was that of Co x Mo 1−x S 2 / C nanohybrids.…”

“…Mesoporous materials with a large specific surface area, narrow pore size distribution, and large pore volume offer abundant active sites and efficient mass/charge transfer . These unique features enable fast ion diffusion, large specific surface area, and enriched adsorption/reaction sites, thus offering a promising solution for designing high-performance electrode materials for next-generation energy storage and conversion devices. − Introducing metal heteroatoms in MoS 2 /C can effectively improve the structural stability of M x Mo 1– x S 2 /C. , …”