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A close correlation between lithofacies and organofacies in meter-scale high-order cycles composed of lacustrine sediments enables comparison and refinement of lithofacies-defined cyclostratigraphy. Four lithofacies and four organofacies have been identified in fluctuating profundal high-order cycles in the lower-Permian Lucaogou Formation, southern Bogda Mountains, NW China. The four lithofacies include interbedded and interlaminated coarse siltstone and very fine sandstone, black shale, wackestone and dolostone, and calcareous and dolomitic shales. Four distinctive organofacies have been identified, on the basis of geochemical composition of organic matter and specific biomarker proxies related to organic matter types, rather than to depositional conditions and thermal maturity. The four organofacies are associated with the four lithofacies in the meter-scale high-order cycles, suggesting litho- and organo-facies may be genetically linked and may have been controlled by lake contraction and extension. The study shows that the lithofacies-derived and environment-defined high-order cycles can be delineated and substantiated by geochemical proxies-defined organofacies. This study also demonstrates that a holistic approach combining litho- and organic geochemical data is useful in reconstruction of meter-scale lacustrine cycles in a half-graben. 

Electrocatalytic hydrogen evolution reaction (HER) is critical for green hydrogen generation and exhibits distinct pH-dependent kinetics that have been elusive to understand. A molecular-level understanding of the electrochemical interfaces is essential for developing more efficient electrochemical processes. Here we exploit an exclusively surface-specific electrical transport spectroscopy (ETS) approach to probe the Pt-surface water protonation status and experimentally determine the surface hydronium pK a = 4.3. Quantum mechanics (QM) and reactive dynamics using a reactive force field (ReaxFF) molecular dynamics (RMD) calculations confirm the enrichment of hydroniums (H 3 O + * ) near Pt surface and predict a surface hydronium pK a of 2.5 to 4.4, corroborating the experimental results. Importantly, the observed Pt-surface hydronium pK a correlates well with the pH-dependent HER kinetics, with the protonated surface state at lower pH favoring fast Tafel kinetics with a Tafel slope of 30 mV per decade and the deprotonated surface state at higher pH following Volmer-step limited kinetics with a much higher Tafel slope of 120 mV per decade, offering a robust and precise interpretation of the pH-dependent HER kinetics. These insights may help design improved electrocatalysts for renewable energy conversion. 

Abstract Direct implementation of metal-organic frameworks as the catalyst for CO 2 electroreduction has been challenging due to issues such as poor conductivity, stability, and limited > 2e − products. In this study, Au nanoneedles are impregnated into a cupric porphyrin-based metal-organic framework by exploiting ligand carboxylates as the Au 3+ -reducing agent, simultaneously cleaving the ligand-node linkage. Surprisingly, despite the lack of a coherent structure, the Au-inserted framework affords a superb ethylene selectivity up to 52.5% in Faradaic efficiency, ranking among the best for metal-organic frameworks reported in the literature. Through operando X-ray, infrared spectroscopies and density functional theory calculations, the enhanced ethylene selectivity is attributed to Au-activated nitrogen motifs in coordination with the Cu centers for C-C coupling at the metalloporphyrin sites. Furthermore, the Au-inserted catalyst demonstrates both improved structural and catalytic stability, ascribed to the altered charge conduction path that bypasses the incoherent framework. This study underlines the modulation of reticular metalloporphyrin structure by metal impregnation for steering the CO 2 reduction reaction pathway.