Electronic Modulation and Mechanistic Study of Ru‐Decorated Porous Cu‐Rich Cuprous Oxide for Robust Alkaline Hydrogen Oxidation and Evolution Reactions

Abstract

Rational design of high‐efficiency and viable electrocatalysts is essential in overcoming the bottleneck of sluggish alkaline hydrogen oxidation/evolution reaction (HOR/HER) kinetics. In this study, a metal‐organic framework‐derived strategy for constructing a Pt‐free catalyst with Ru clusters anchored on porous Cu−Cu2O@C is proposed. The designed Ru/Cu−Cu2O@C exhibits superior HOR performance, with a mass activity of 2.7 mA μgRu-1 ${{{\rm \mu }{\rm g}}_{{\rm R}{\rm u}}^{-1}}$ at 50 mV, which is about 24 times higher than that of state‐of‐the‐art Pt/C (0.11 mA μgPt-1 ${{{\rm \mu }{\rm g}}_{{\rm P}{\rm t}}^{-1}}$ ). Significantly, Ru/Cu−Cu2O@C also displays impressive HER performance by generating 26 mV at 10 mA cm−2, which exceeds the majority of documented Ru‐based electrocatalysts. Systematic characterization and density functional theory (DFT) calculations reveal that efficient electron transfer between Ru and Cu species results in an attenuated hydrogen binding energy (HBE) of Ru and an enhanced hydroxy binding energy (OHBE) of Cu2O, together with an optimized H2O adsorption energy with Cu2O as the H2O*‐capturing site, which jointly facilitates HOR and HER kinetics.

Electronic metal–support interaction via Ni defect-induced Ru-modified Ni–CeO2 for enhanced hydrogen oxidation activity

“…1e) exhibited lattice fringes for the Ru/Ni-CeO 2 microspheres of 2.03, 2.34 and 3.12 Å, representing the (111) plane of Ni, the (100) plane of Ru, and the (111) plane of CeO 2 , respectively. 14 The coexistence of Ni, Ru, and CeO 2 components confirmed the successful fabrication of Ru/Ni-CeO 2 catalysts. Elemental mapping analysis presented in Fig.…”

“…25 Notably, the binding energy of Ru species in Ru/Ni–CeO 2 was lower than that in Ru/CeO 2 , indicating electronic interaction between Ru and Ni–CeO 2 . 14 In Fig. 3b, four deconvoluted peaks at 853.3, 856.9, 859.5 and 863.2 eV were associated with Ni 0 , Ni 2+ , Ni 3+ and satellite peak species, respectively.…”

“…20 The abundant nickel vacancies in Ru/Ni-CeO 2 dramatically tuned the local electronic structure, thus increasing the charge-carrier concentration, accelerating charge transfer and improving the catalytic activity. 17 19,22 Meanwhile, deconvolution peaks near 281.0 and 285.1 eV represented 3d 5/2 and 3d 3/2 of metal Ru, respectively, 23 and the peaks at about 282.4 and 286.6 eV were 3d 5/2 and 3d 3/2 of RuO 2 , respectively, owing to unavoidable oxidation by exposure to air. 24 Additionally, the high-resolution XPS spectra of Ru 3p further revealed the valence state of Ru.…”

“…The optimal Ru content likely promotes a homogeneous distribution of Ru, thereby maximizing active site exposure, which is consistent with previous reports. 35,36 Subsequently, the electrocatalytic performances of the synthesized Ni-CeO 2 , Ru/Ni, Ru/CeO 2 , and Ru/Ni-CeO 2 , commercial Ru/C, and benchmark Pt/C were studied under identical conditions for comparison. As observed from the HOR polarization curves (Fig.…”

RuSe2/CeO2 heterostructure as a novel electrocatalyst for highly efficient alkaline hydrogen evolution

“…Note that the peak at 531.2 eV of RuSe 2 /CeO 2 has a strong binding energy compared to that of CeO 2 , which reveals that the presence of CeO 2 can promote the ability of water adsorption of RuSe 2 /CeO 2 [2]. Compared with CeO 2 and RuSe 2 , the shifts of Ru 3p, Ru 3d in RuSe 2 /CeO 2 to low binding energies and the shifts of Ce 3d 5/2 and O 1s to high binding energies in RuSe 2 /CeO 2 indicates the existence an electronic interaction between RuSe 2 and CeO 2 , implying that CeO 2 can modulate the electronic structure of RuSe 2 species [52,53]. The results of the above analysis show that the existence of heterogeneous interface can lead to electron redistribution, which is conducive to improving the inherent activity of the electrocatalyst.…”