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Water is the only available fossil-free source of hydrogen. Splitting water electrochemically is among the most used techniques, however, it accounts for only 4% of global hydrogen production. One of the reasons is the high cost and low performance of catalysts promoting the oxygen evolution reaction (OER). Here, we report a highly efficient catalyst in acid, that is, solid-solution Ru‒Ir nanosized-coral (RuIr-NC) consisting of 3 nm-thick sheets with only 6 at.% Ir. Among OER catalysts, RuIr-NC shows the highest intrinsic activity and stability. A home-made overall water splitting cell using RuIr-NC as both electrodes can reach 10 mA cm −2 geo at 1.485 V for 120 h without noticeable degradation, which outperforms known cells. Operando spectroscopy and atomic-resolution electron microscopy indicate that the high-performance results from the ability of the preferentially exposed {0001} facets to resist the formation of dissolvable metal oxides and to transform ephemeral Ru into a long-lived catalyst. Ru is one of the most active metals for oxygen evolution reaction, but it quickly dissolves in acidic electrolyte particularly in nanosized form. Here, the authors show that coral-like solid-solution Ru‒Ir consisting of 3 nm-thick sheets with only 6 at% Ir is a long-lived catalyst with high activity.

Binary solid-solution alloys generally adopt one of three principal crystal lattices—body-centred cubic (bcc), hexagonal close-packed (hcp) or face-centred cubic (fcc) structures—in which the structure is dominated by constituent elements and compositions. Therefore, it is a significant challenge to selectively control the crystal structure in alloys with a certain composition. Here, we propose an approach for the selective control of the crystal structure in solid-solution alloys by using a chemical reduction method. By precisely tuning the reduction speed of the metal precursors, we selectively control the crystal structure of alloy nanoparticles, and are able to selectively synthesize fcc and hcp AuRu 3 alloy nanoparticles at ambient conditions. This approach enables us to design alloy nanomaterials with the desired crystal structures to create innovative chemical and physical properties. The crystal structure of a solid-solution alloy is generally determined by its elemental composition, limiting synthetic control over the alloy’s properties. Here, the authors are able to selectively control the crystal structure of Au–Ru alloy nanoparticles by rationally tuning the reduction speed of the metal precursors.

While previous teacher education research on argumentation primarily targeted science teachers, we will provide insights on where to begin teacher education for beginners in situations, where argumentation instruction is not yet common and time constraints impede teacher training. We conducted a short-term program that lasted 160 minutes, with 61 graduate students from a Japanese graduate school of teacher education as participants. It explained arguments, and taught the participants how to construct, score, and plan arguments that they could use in their classes. We conducted the argument construction and evaluation task to examine the presence or absence of components and the correctness of the arguments. The non-parametric quantitative response data were analyzed using SPSS by Wilcoxon signed rank-sum test and Mann-Whitney U test. The results showed that the post-test revealed significant improvements in both tasks. This program may be effective for non-science beginner teachers.

Socioscientific issues (SSIs) provide meaningful contexts for developing students’ competencies in scientific evaluation and decision-making. This study developed an SSI-based instructional unit to support primary school students in making decisions about genome-edited fish by considering risks and benefits and proposing risk mitigation. The study aimed to examine the unit’s effectiveness in improving students’ risk-related decision-making and their attitudes toward critical thinking and risk. Sixty-three fifth-grade students participated in an 18-lesson unit comprising two phases: information gathering and risk management practice. Students completed three decision-making tasks and a post-unit questionnaire on related attitudes. Written arguments were analysed using a rubric based on claims, risk knowledge, benefit knowledge, and risk mitigation. The results indicated that the unit improved the quality of students’ socioscientific arguments. By the final task, about 60% of arguments reached the highest level, demonstrating integration of risk knowledge and corresponding mitigation. However, students’ risk–benefit emphasis ratings showed that their decisions remained predominantly risk-focused, and questionnaire data revealed a persistent zero-risk mindset. These findings provide empirical evidence that an SSI-based unit incorporating risk management practice can foster primary students’ risk-related socioscientific decision-making. Further refinement is needed to shift students’ risk attitudes and support more balanced risk–benefit reasoning.

Hydrogen has the potential to power much of the modern world with only water as a by-product, but storing hydrogen safely and efficiently in solid form such as magnesium hydride remains a major obstacle. A significant challenge has been the difficulty of proving the hydriding/dehydriding mechanisms and, therefore, the mechanisms have long been the subject of debate. Here we use in situ ultra-high voltage transmission electron microscopy (TEM) to directly verify the mechanisms of the hydride decomposition of bulk MgH 2 in Mg-Ni alloys. We find that the hydrogen release mechanism from bulk (2 μm) MgH 2 particles is based on the growth of multiple pre-existing Mg crystallites within the MgH 2 matrix, present due to the difficulty of fully transforming all Mg during a hydrogenation cycle whereas, in thin samples analogous to nano-powders, dehydriding occurs by a ‘shrinking core’ mechanism.

The triple phase boundary (TPB) of metal, oxide, and gas phases in the anode of solid oxide fuel cells plays an important role in determining their performance. Here we explore the TPB structures from two aspects: atomic-resolution microscopy observation and reaction dynamics simulation. Experimentally, two distinct structures are found with different contact angles of metal/oxide interfaces, metal surfaces, and pore opening sizes, which have not previously been adopted in simulations. Reaction dynamics simulations are performed using realistic models for the hydrogen oxidation reaction (HOR) at the TPB, based on extensive development of reactive force field parameters. As a result, the activity of different structures towards HOR is clarified, and a higher activity is obtained on the TPB with smaller pore opening size. Three HOR pathways are identified: two types of hydrogen diffusion processes, and one type of oxygen migration process which is a new pathway. The triple phase boundary structure in solid-oxide fuel cells largely determines the thermodynamics and kinetics of electrochemical processes therein. Here the authors use atomic-resolution microscopy and reaction dynamics simulation to reveal three discrete hydrogen oxidation reaction pathways.

In science education, the improvement in students’ ability to construct arguments at the primary school level has been reported. Although these studies have identified difficulties in arguments written by primary school students, they do not indicate areas that require improvement in teaching methods. This study aims to explore the possibility of improvement in early primary school students’ ability to construct arguments and identify the types of difficulties encountered. Sixty-seven Japanese third-grade students (9–10 years old) were taught to write arguments as specified by Zembal-Saul et al. (2012). The students were given two writing tasks before and after the lesson. To examine the students’ written arguments, each component of claim, evidence, and reasoning was scored based on a rubric. On comparing the scores of the pre-test and post-test writing tasks, it was found that 27 out of 67 students still had difficulty writing arguments during the post-test. An analysis of the students’ writing revealed four types of difficulties: ‘Incompleteness of components’, ‘Inappropriateness of components’, ‘Confusion between evidence and reasoning’, and ‘Confusion between claim and evidence’. This study offers insights pertaining to teaching implications and research recommendations.

In a comment on our Article “Evidence of the hydrogen release mechanism in bulk MgH 2 ”, Surrey et al . assert that the MgH 2 sample we studied was not MgH 2 at any time but rather MgO; and that the transformation we observed was the formation of Kirkendall voids due to the outward diffusion of Mg. We address these issues in this reply.

Cu6Sn5 is an important intermetallic compound in soldering and electronic packaging. It is formed at the interface between molten solder and substrate during the soldering process, and the evolution of microstructure and properties also occurs in service. Previous studies revealed that Au and Ni are stabilization alloying elements for hexagonal η-Cu6Sn5 intermetallic. For better understanding of stabilization mechanisms at atomic resolution level, in this work, we made an attempt atomic structure analysis on a stoichiometric (Cu, Au, Ni)6Sn5 intermetallic prepared by direct alloying. High-angle annular dark-field (HAADF) imaging and atomic-resolution chemical mapping were taken by the aberration-corrected (Cs-corrected) scanning transmission electron microscopy (STEM). It is found that Au and Ni doped Cu6Sn5 has hexagonal structure. The atom sites of Cu1 and Sn can be distinguished in atomic-resolution images after being observed from orientation [2110], which is also confirmed by atomic-resolution chemical mapping analysis. Importantly, atomic-resolution about distribution of alloying Au atom was directly observed, and Au atoms occupy the Cu1 sites in η-Cu6Sn5.