Yun-Fei Xu

The critical role of non-covalent van der Waals (vdW) interactions in determining the relative stability of alkoxy intermediates has been demonstrated for the Cu(110) surface using a combination of experiment and theory. The results may be significant for the selectivity control of copper-based reactions of alcohols. Previous examination of this effect on Au(110) was also extended to include higher molecular weight alcohols; on Cu(110) and Au(110) the hierarchy for the strength of binding of the alkoxys was found to be the same within experimental accuracy, with alkoxy species of greater chain length being more stable. The equilibrium constants governing the competition of alcohol pairs for binding sites of the alkoxys are also similar on the two surfaces. These results reveal the generality of such vdW effects. This work expands the understanding of the role of vdW interactions on the binding efficacy of key reactive intermediates on metal surfaces – a key factor in the rational design of complex and selective catalytic processes.

Enhancing the selectivity of catalytic processes has potential for substantially increasing the sustainability of chemical production. Herein, we establish relationships between reaction selectivity and molecular structure for a homologous series of key intermediates for oxidative coupling of alcohols on gold using a combination of experiment and theory. We establish a scale of binding for molecules with different alkyl structures and chain lengths and thereby demonstrate the critical nature of noncovalent van der Waals interactions in determining the selectivity by modulating the stability of key reaction intermediates bound to the surface. The binding hierarchy is the same for Au(111) and Au(110), which demonstrates a relative lack of sensitivity to the surface structure. The hierarchy of binding established in this work provides guiding principles for predicting how molecular structure affects the competition for binding sites more broadly. Besides the nature of the primary surface-molecule bonding, three additional factors that affect the stabilities of the reactive intermediates are clearly established: (1) the number of C atoms in the alkyl chain, (2) the presence of C–C bond unsaturation, and (3) the degree of branching of the alkyl group of the adsorbed molecules. We suggest that this is a fundamental principle that is generally applicable to a broad range of reactions on metal catalysts.

The electroreduction of water for sustainable hydrogen production is a critical component of several developing clean-energy technologies, such as water splitting and fuel cells. However, finding a cheap and efficient alternative catalyst to replace currently used platinum-based catalysts is still a prerequisite for the commercialization of these technologies. Here we report a robust and highly active catalyst for hydrogen evolution reaction that is constructed by in situ growth of molybdenum disulfide on the surface of cobalt diselenide. In acidic media, the molybdenum disulfide/cobalt diselenide catalyst exhibits fast hydrogen evolution kinetics with onset potential of −11 mV and Tafel slope of 36 mV per decade, which is the best among the non-noble metal hydrogen evolution catalysts and even approaches to the commercial platinum/carbon catalyst. The high hydrogen evolution activity of molybdenum disulfide/cobalt diselenide hybrid is likely due to the electrocatalytic synergistic effects between hydrogen evolution-active molybdenum disulfide and cobalt diselenide materials and the much increased catalytic sites.

The slow kinetics of the oxygen evolution reaction (OER) greatly hinders the large-scale production of hydrogen fuel from water splitting. Although many OER electrocatalysts have been developed to negotiate this difficult reaction, substantial progresses in the design of cheap, robust, and efficient catalysts are still required and have been considered a huge challenge. Here, we report a composite material consisting of CoSe₂ nanobelts anchored on nitrogen-doped reduced graphene oxides (denoted as NG-CoSe₂) as a highly efficient OER electrocatalyst. In 0.1 M KOH, the new NG-CoSe₂ catalyst afforded a current density of 10 mA cm^–2 at a small overpotential of mere 0.366 V and a small Tafel slope of ∼40 mV/decade, comparing favorably with the state-of-the-art RuO₂ catalyst. This NG-CoSe₂ catalyst also presents better stability than that of RuO₂ under harsh OER cycling conditions. Such good OER performance is comparable to the best literature results and the synergistic effect was found to boost the OER performance. These results raise the possibility for the development of effective and robust OER electrodes by using cheap and easily prepared NG-CoSe₂ to replace the expensive commercial catalysts such as RuO₂ and IrO₂.

Developing a reliable technique to organize nanoscale building blocks into ordered one‐dimensional assemblies is of particular interest in a range of practical applications. Here, for the first time, it is reported that platinum (Pt) nanoparticle chain networks can be assembled spontaneously in solution on a large scale. The in‐situ induced magnetic dipoles are believed to be the driving force for producing such elegant assembled nanochains. The alterant electronic structure of Pt modified by a very thin layer of polyvinylpyrrolidone (PVP) molecules leads to the ferromagnetism of Pt (a traditional paramagnetic metal), which has been verified by a series of analysis techniques and theoretical modeling. The temperature‐ and time‐dependent nucleation, growth, and organization processes of Pt chain networks are carefully investigated. These findings not only present the uncommon ferromagnetism of Pt, but also raise a possibility for expanding this strategy towards other assemblies of nonmagnetic nanoscale building blocks.

Advanced energy conversion and storage (ECS) devices (including fuel cells, photoelectrochemical water splitting cells, solar cells, Li-ion batteries and supercapacitors) are expected to play a major role in the development of sustainable technologies that alleviate the energy and environmental challenges we are currently facing. The successful utilization of ECS devices depends critically on synthesizing new nanomaterials with merits of low cost, high efficiency, and outstanding properties. Recent progress has demonstrated that nanostructured metal chalcogenides (MCs) are very promising candidates for efficient ECS systems based on their unique physical and chemical properties, such as conductivity, mechanical and thermal stability and cyclability. In this review, we aim to provide a summary on the liquid-phase synthesis, modifications, and energy-related applications of nanostructured metal chalcogenide (MC) materials. The liquid-phase syntheses of various MC nanomaterials are primarily categorized with the preparation method (mainly 15 kinds of methods). To obtain optimized, enhanced or even new properties, the nanostructured MC materials can be modified by other functional nanomaterials such as carbon-based materials, noble metals, metal oxides, or MCs themselves. Thus, this review will then be focused on the recent strategies used to realize the modifications of MC nanomaterials. After that, the ECS applications of the MC/modified-MC nanomaterials have been systematically summarized based on a great number of successful cases. Moreover, remarks on the challenges and perspectives for future MC research are proposed (403 references).