Characterisation of Conventional 87Sr/86Sr Isotope Ratios in Cement, Limestone and Slate Reference Materials Based on an Interlaboratory Comparison Study

An interlaboratory comparison (ILC) was organised to characterise 87Sr/86Sr isotope ratios in geological and industrial reference materials by applying the so-called conventional method for determining 87Sr/86Sr isotope ratios. Four cements (VDZ 100a, VDZ 200a, VDZ 300a, IAG OPC-1), one limestone (IAG CGL ML-3) and one slate (IAG OU-6) reference materials were selected, covering a wide range of naturally occurring Sr isotopic signatures. Thirteen laboratories received aliquots of these six reference materials together with a detailed technical protocol. The consensus values for the six reference materials and their associated measurement uncertainties were obtained by applying a Gaussian, linear mixed effects model fitted to all the measurement results. By combining the consensus values and their uncertainties with an uncertainty contribution for potential heterogeneity, reference values ranging from 0.708134 mol mol-1 to 0.729778 mol mol-1 were obtained with relative expanded uncertainties of ≤ 0.007 %. This study represents an ILC on conventional 87Sr/86Sr isotope ratios, within which metrological principles were considered and the compatibility of measurement results obtained by MC-ICP-MS and by MC-TIMS is demonstrated. The materials characterised in this study can be used as reference materials for validation and quality control purposes and to estimate measurement uncertainties in conventional 87Sr/86Sr isotope ratio measurement

Synergistic Catalytic Sites in High Entropy Metal Hydroxide Organic Framework for Oxygen Evolution Reaction

The integration of multiple elements in a high entropy state is crucial in the design of high performance, durable electrocatalysts. High entropy metal hydroxide organic frameworks HE MHOFs are synthesized under mild solvothermal conditions. This novel crystalline metal organic framework MOF features a random, homogeneous distribution of cations within high entropy hydroxide layers. HE MHOF exhibits excellent electrocatalytic performance for the oxygen evolution reaction OER , reaching a current density of 100 mA cm amp; 8722;2 at amp; 8776;1.64 VRHE, and demonstrates remarkable durability, maintaining a current density of 10 mA cm amp; 8722;2 for over 100 h. Notably, HE MHOF outperforms precious metal based electrocatalysts despite containing only amp; 8776;60 OER active metals. Ab initio calculations and operando X ray absorption spectroscopy XAS demonstrate that the high entropy catalyst contains active sites that facilitate a multifaceted OER mechanism. This study highlights the benefits of high entropy MOFs in developing noble metal free electrocatalysts, reducing reliance on precious metals, lowering metal loading especially for Ni, Co, and Mn , and ultimately reducing costs for sustainable water electrolysis technologie