Single-atom nickel dopants anchored to three-dimensional nanoporous graphene can be used as catalysts of the hydrogen evolution reaction (HER) in acidic solutions. In contrast to conventional nickel-based catalysts and graphene, this material shows superior HER catalysis with a low overpotential of approximately 50 mV and a Tafel slope of 45 mV dec(-1) in 0.5 M H2SO4 solution, together with excellent cycling stability. Experimental and theoretical investigations suggest that the unusual catalytic performance of this catalyst is due to sp-d orbital charge transfer between the Ni dopants and the surrounding carbon atoms. The resultant local structure with empty C-Ni hybrid orbitals is catalytically active and electrochemically stable.

Nanoporous bimetallic (Co1−xFex)2P phosphides with tuneable Co/Fe ratios exhibit versatile catalytic activities for highly efficient electrochemical water splitting.

Designing efficient electrocatalysts for hydrogen evolution reaction is significant for renewable and sustainable energy conversion. Here, we report single-atom platinum decorated nanoporous Co 0 . 85 Se (Pt/np-Co 0 . 85 Se) as efficient electrocatalysts for hydrogen evolution. The achieved Pt/np-Co 0 . 85 Se shows high catalytic performance with a near-zero onset overpotential, a low Tafel slope of 35 mV dec −1 , and a high turnover frequency of 3.93 s −1 at −100 mV in neutral media, outperforming commercial Pt/C catalyst and other reported transition-metal-based compounds. Operando X-ray absorption spectroscopy studies combined with density functional theory calculations indicate that single-atom platinum in Pt/np-Co 0 . 85 Se not only can optimize surface states of Co 0 . 85 Se active centers under realistic working conditions, but also can significantly reduce energy barriers of water dissociation and improve adsorption/desorption behavior of hydrogen, which synergistically promote thermodynamics and kinetics. This work opens up further opportunities for local electronic structures tuning of electrocatalysts to effectively manipulate its catalytic properties by an atomic-level engineering strategy.

The "edge-free" monolayer MoS2 films supported by 3D nanoporous gold show high catalytic activities towards hydrogen evolution reaction (HER), originating from large out-of-plane strains that are geometrically required to manage the 3D curvature of bicontinuous nanoporosity. The large lattice bending leads to local semiconductor-to-metal transition of 2H MoS2 and the formation of catalytically active sites for HER.

Terahertz technology promises broad applications, which calls for terahertz electromagnetic interference (EMI) shielding materials to alleviate radiation pollution. 2D transition metal carbides and/or nitrides (MXenes) with metallic conductivity are promising for EMI shielding, but simultaneously realizing light weight, high stability, and foldability in a MXene shielding material to meet the requirements of increasingly popular portable and wearable equipment has remained a great challenge. Herein, an ion-diffusion-induced gelation method is demonstrated to synthesize free-standing, light-weight, foldable, and highly stable MXene foams, in which MXene sheets are cross-linked by multivalent metal ions and graphene oxide to form an oriented porous structure. The method is highly efficient, controllable, and versatile for scalable generation of functional 3D MXene structures with arbitrary shapes and synergistic properties. The distinctive cross-linked porous structure endows the light-weight MXene foam with good foldability, outstanding durability and stability in wet environments, and an excellent terahertz shielding effectiveness of 51 dB at a small thickness of 85 μm. This work not only provides an insight for the on-target design of high-performance terahertz shielding materials but also expands the applications of MXenes in 3D macroscopic form.

The electrochemical nitrogen reduction reaction (NRR) process usually suffers extremely low Faradaic efficiency and ammonia yields due to sluggish NN dissociation. Herein, single‐atomic ruthenium modified Mo2CTX MXene nanosheets as an efficient electrocatalyst for nitrogen fixation at ambient conditions are reported. The catalyst achieves a Faradaic efficiency of 25.77% and ammonia yield rate of 40.57 µg h−1 mg−1 at ‐0.3 V versus the reversible hydrogen electrode in 0.5 m K2SO4 solution. Operando X‐ray absorption spectroscopy studies and density functional theory calculations reveal that single‐atomic Ru anchored on MXene nanosheets act as important electron back‐donation centers for N2 activation, which can not only promote nitrogen adsorption and activation behavior of the catalyst, but also lower the thermodynamic energy barrier of the first hydrogenation step. This work opens up a promising avenue to manipulate catalytic performance of electrocatalysts utilizing an atomic‐level engineering strategy.

Hydrogen production from electrochemical water splitting is a promising route to pursue clean and sustainable energy sources. Here, a three-dimensional nanoporous Cu−Ru alloy is prepared as a high-performance platinum-free catalyst for hydrogen evolution reaction (HER) by a dealloying process. Significantly, the optimized nanoporous alloy Cu 53 Ru 47 exhibits remarkable catalytic activity for HER with nearly zero onset overpotential and ultralow Tafel slopes (∼30 and ∼35 mV dec −1 ) in both alkaline and neutral electrolytes, achieving a catalytic current density of 10 mA cm −2 at low overpotentials of ∼15 and ∼41 mV, respectively. Operando Xray absorption spectroscopy experiments, in conjunction with DFT simulations, reveal that the incorporation of Ru atoms into the Cu matrix not only accelerates the reaction step rates of water adsorption and activation but also optimizes the hydrogen bonding energy on Cu and Ru active sites, improving the intrinsic activity for HER.

Three-dimensional (3D) metallic microstructures with wellcontrolled hierarchical morphologies down to the sub-micrometer scale have attracted considerable attention.[1] These structures have broad applications owing to their unique optical, [2a] electronic, [2b] magnetic, [2c] thermal, [2d,e] and catalytic [2f] properties, which can be modulated by their intrinsic microstructures. Such structures, however, are quite difficult to prepare by traditional methods. One promising route to create these metallic structures is direct replication from hierarchical structures of various natural species. Metals have been physically deposited onto biological structures to fabricate metallic structures through physical vapor deposition (PVD).[3] However, the line-of-sight nature of PVD prevented a complete replication of the biotemplates original 3D morphologies.[4] Some groups elegantly converted natural inorganic structures such as diatom frustules into metals (Ag, Au, Pd) using wet-chemical processes, [4] but many natural species with functional structures are composed of organic materials. Versatile synthesis of metallic structures using organic-based natural species intact, 3D, and hierarchical sub-micrometer morphologies as templates is thus needed.Herein we present a versatile route (selective surface functionalization and subsequent electroless deposition) to generate metallic replicas of the intact 3D organic butterfly (Euploea mulciber) wing scales. This method can replicate the original chitin-based scales morphology in at least seven important metals, including cobalt, nickel, copper, palladium, silver, platinum, and gold ( Figure 1 and Figure 2). Significantly, using the synthetic Au scale as a surface-enhanced Raman scattering (SERS) substrate, the detectable analyte concentration (Rhodamine 6G, 10 À13 m) can be one order of magnitude lower than using commercial substrates (Klarite). To our knowledge, this work is the first demonstration of the conversion of intact hierarchical 3D butterfly structures on a sub-micrometer level into metallic replicas. It should be noted that butterflies belong to the order Lepidoptera (Latin word for "scaly wing", including butterflies and moths) that comprises an estimated 174 250 species.[5] A given species usually has more than one type of wing scale, [6] and such huge morphological diversity offers a vast structure pool for biotemplate selection (e.g., photonic crystal design).[7a] In addition, chitin, the main component of butterfly wing scales, is one of the richest natural macromolecular compounds. [8] Therefore, this approach can be extended to replicate other chitin-based biostructures, including fungi cell walls, exoskeletons of insects [9a,b] and arthropods (e.g., crabs and lobsters), [9c] radulas of mollusks (e.g., snails), and beaks of cephalopods (e.g., squids [9d] and octopuses). The fabrication route described herein consists of three steps (see Scheme S1 in the Supporting Information): 1) func- Figure 1. SEM element mapping images of seven metallic win...