Oxygen Radical Coupling on Short-Range Ordered Ru Atom Arrays Enables Exceptional Activity and Stability for Acidic Water Oxidation

The discovery of efficient and stable electrocatalysts for oxygen evolution reaction (OER) in acid is vital for the commercialization of the proton-exchange membrane water electrolyzer. In this work, we demonstrate that short-range Ru atom arrays with near-ideal Ru–Ru interatomic distances and a unique Ru–O hybridization state can trigger direct O*–O* radical coupling to form an intermediate O*–O*-Ru configuration during acidic OER without generating OOH* species. Further, the Ru atom arrays suppress the participation of lattice oxygen in the OER and the dissolution of active Ru. Benefiting from these advantages, the as-designed Ru array-Co3O4 electrocatalyst breaks the activity/stability trade-off that plagues RuO2-based electrocatalysts, delivering an excellent OER overpotential of only 160 mV at 10 mA cm–2 in 0.5 M H2SO4 and outstanding durability during 1500 h operation, representing one of the best acid-stable OER electrocatalysts reported to date. 18O-labeled operando spectroscopic measurements together with theoretical investigations revealed that the short-range Ru atom arrays switched on an oxide path mechanism (OPM) during the OER. Our work not only guides the design of improved acidic OER catalysts but also encourages the pursuit of short-range metal atom array-based electrocatalysts for other electrocatalytic reactions

RuO₂–CeO₂ Lattice Matching Strategy Enables Robust Water Oxidation Electrocatalysis in Acidic Media via Two Distinct Oxygen Evolution Mechanisms

The discovery of acid-stable and highly active electrocatalysts for the oxygen evolution reaction (OER) is crucial in the quest for high-performance water-splitting technologies. Herein, a heterostructured RuO2–CeO2 electrocatalyst was constructed by using a lattice-matching strategy. The interfacial Ru–O–Ce bridge structure provided a channel for electron transfer between Ru and Ce, creating a lattice stress that distorts the local structure of RuO2. The resulting RuO2–CeO2 catalyst exhibited attractive stability with negligible decay after 1000 h of the OER in 0.5 M H2SO4, along with high activity with an overpotential of only 180 mV at 10 mA cm–2. In situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), in situ differential electrochemical mass spectrometry (DEMS), and density functional theory (DFT) calculations were used to reveal that the interface and noninterface RuO2 sites enabled an oxide path mechanism (OPM) and the enhanced adsorbate evolution mechanism (AEM-plus), respectively, during the OER. The simultaneous and independent OER pathways accessible by lattice matching guides improved electrocatalyst design for the OER in acidic media

Metal-Free Polyphthalocyanine with Implanted Built-In Electric Field Enabling High-Efficiency CO₂ Electroreduction

Metal phthalocyanine (Pc)-based molecular catalysts are able to achieve an efficient carbon dioxide electroreduction reaction. Nonetheless, the further development of metal Pc is greatly limited by reserves and geographical distribution differentiation of metal strategic resources, such as Co and Ni. Herein, a metal-free polyphthalocyanine/carbon tube (PPc/CNT) electrocatalyst was activated by a double electron transfer strategy and creatively exhibited a performance comparable to that of metal Pc-based electrocatalysts. The electron-rich charge state of the PPc/CNT catalyst generated by the built-in electric field induced a unique CO2-dependent response, in which the adsorbed CO2 on its surface trapped the free electrons from PPc/CNT, accompanied by a switch from an electron-rich to an electron-deficient feature, thus restraining the hydrogen evolution reaction. The PPc/CNT with an electron-rich carbon site can still keep over 95% of the high CO Faradaic efficiency in a wide potential region of 600 mV, superior to that of reported Pc-based electrocatalysts. Theoretical studies revealed that the C site (adjacent to two N sites in pyrrolic N and C–NC) in the catalyst featured low CO2 adsorption energy and enhanced CO2 activation capability compared with that of two N sites, being the intrinsically active center