The emergence of zerovalent atom catalysts has been highly attractive for catalytic science. For many years, scientists have explored the stability of zerovalent atom catalysts and demonstrated their unique properties. Here, we describe an atom catalyst (AC) with atomically dispersed zerovalent molybdenum atoms on graphdiyne (Mo 0 /GDY) with a high mass content of Mo atoms (up to 7.5 wt %) that was synthesized via a facile and scalable process. The catalyst shows both excellent selectivity and activity in the electrochemical reduction of nitrogen and in the hydrogen evolution reaction in aqueous solutions at room temperature and pressure. It is noted that this catalyst is the first bifunctional AC for highly efficient and selective ammonia and hydrogen generation. The catalytic process of our catalyst is well understood, the structure is defined, and the performance is excellent, providing a solid foundation for the generation and application of the new generation of catalysts.

The generation of intense coherent deep-UV light from nonlinear optical materials is crucial to applications ranging from semiconductor photolithography and laser micromachining to photochemical synthesis. However, few materials with large second harmonic generation (SHG) and a short UV-cutoff edge are effective down to 200 nm. A notable exception is KBe2BO3F2, which is obtained from a solid-state reaction of highly toxic beryllium oxide powders. We designed and synthesized a benign polar material, Ba4B11O20F, that satisfies these requirements and exhibits the largest SHG response in known borates containing neither lone-pair-active anions nor second-order Jahn-Teller-active transition metals. We developed a microscopic model to explain the enhancement, which is unexpected on the basis of conventional anionic group theory arguments. Crystal engineering of atomic displacements along the polar axis, which are difficult to attribute to or identify within unique anionic moieties, and greater cation polarizabilities are critical to the design of next-generation SHG materials.

Deep ultraviolet (absorption edge <200 nm, band gap >6.2 eV) nonlinear optical (NLO) materials are of current interest owing to their technological applications and materials design challenges. Technologically, the materials are used in laser systems, atto-second pulse generation, semiconductor manufacturing, and photolithography. Designing and synthesizing a deep UV NLO material requires crystallographic noncentrosymmetry, a wide UV transparency range, a large second-harmonic generating coefficient (d ij > 0.39 pm/V), moderate birefringence (Δn ∼ 0.07), chemical stability and resistance to laser damage, and ease in the growth of large high-quality single crystals. This review examines the known deep UV NLO materials with respect to their crystal structure, band gap, SHG efficiency, laser damage threshold, and birefringence. Finally, future directions with respect to new deep UV NLO materials are discussed.