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Chemical energy conversion/storage through water splitting for hydrogen production has been recognized as the ideal solution to the transient nature of renewable energy sources. Solid polymer electrolyte (SPE) water electrolysis is one of the most practical ways to produce pure H2. Electrocatalysts are key materials in the SPE water electrolysis. At the anode side, electrode materials catalyzing the oxygen evolution reaction (OER) require specific properties. Among the reported materials, only iridium presents high activity and is more stable. In this Minireview, an application overview of single iridium metal and its oxide catalysts—binary, ternary, and multicomponent catalysts of iridium oxides and supported composite catalysts—for the OER in SPE water electrolysis is presented. Two main strategies to improve the activity of an electrocatalyst system, namely, increasing the number of active sites and the intrinsic activity of each active site, are reviewed with detailed examples. The challenges and perspectives in this field are also discussed.

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Recently, paper substrates have attracted tremendous interest from both academia and industry. Not only is paper highly abundant and portable, it is lightweight, disposable, easy-to-use, and can be rolled or folded into 3D configurations. More importantly, with a unique porous bulk structure and rough and absorptive surface properties, the construction of nanomaterials-functionalized cellulose has enabled cellulose paper to be applied for point-of-care (POC) paper devices with reasonably good performance at low cost. In this review, the latest advances in the modification of nanomaterials on paper cellulose are summed up. To begin with, the attractive properties of paper-based analytical devices are described. Then, fabricating methods for the functionalization of cellulose with diverse materials, including noble metals, bimetals, metal oxides, carbon nanomaterials, and molecular imprinting polymer nanoparticles, as well as their applications, are introduced in detail. Finally, the current critical issues, challenges, and future prospectives for exploring a paper-based analytical system based on nanomaterials-modified cellulose are discussed. It is believed that more strategies will be developed in the future to construct nanomaterials-functionalized cellulose, paving the way for the mass production of POC paper devices with a satisfactory performance.

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Using remote N plasma treatment to promote dielectric deposition on the dangling-bond free MoS is explored for the first time. The N plasma induced damages are systematically studied by the defect-sensitive acoustic-phonon Raman of single-layer MoS, with samples undergoing O plasma treatment as a comparison. O plasma treatment causes defects in MoS mainly by oxidizing MoS along the already defective sites (most likely the flake edges), which results in the layer oxidation of MoS. In contrast, N plasma causes defects in MoS mainly by straining and mechanically distorting the MoS layers first. Owing to the relatively strong MoS-substrate interaction and chemical inertness of MoS in N plasma, single-layer MoS shows great stability in N plasma and only stable point defects are introduced after long-duration N plasma exposure. Considering the enormous vulnerability of single-layer MoS in O plasma and the excellent stability of single-layer MoS in N plasma, the remote N plasma treatment shows great advantage as surface functionalization to promote dielectric deposition on single-layer MoS.

Graphene and its related materials remain a very bright and exciting prospect in analytical chemistry.