Developing cost-effective electrocatalysts operated in the same electrolyte for water splitting, including oxygen and hydrogen evolution reactions, is important for clean energy technology and devices. Defects in electrocatalysts strongly influence their chemical properties and electronic structures, and can dramatically improve electrocatalytic performance. However, the development of defect-activated electrocatalyst with an efficient and stable water electrolysis activity in alkaline medium remains a challenge, and the understanding of catalytic origin is still limited. Here, we highlight defect-enriched bifunctional eletrocatalyst, namely, three-dimensional iron fluoride-oxide nanoporous films, fabricated by anodization/fluorination process. The heterogeneous films with high electrical conductivity possess embedded disorder phases in crystalline lattices, and contain numerous scattered defects, including interphase boundaries, stacking faults, oxygen vacancies, and dislocations on the surfaces/interface. The heterocatalysts efficiently catalyze water splitting in basic electrolyte with remarkable stability. Experimental studies and first-principle calculations suggest that the surface/edge defects contribute significantly to their high performance.

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Boron nanoclusters and few‐layer borophenes have received considerable attention in recent years due to their unique structural and bonding patterns. Based on extensive global searches and density‐functional theory calculations, we present herein the possibility of a new series of bilayer medium‐sized boron clusters including C2 B54 (I), C2h B60 (II), and C1 B62 (III) in a universal structural pattern, with one, two, and three B6 hexagonal windows on the waist around a B38 bilayer hexagonal prism at the center, respectively. Detailed orbital and bonding analyses indicate that these three‐dimensional aromatic bilayer clusters follow the σ + π double delocalization bonding pattern, with three or four effective interlayer B–B σ‐bonds formed to further stabilize the system. The IR, Raman, and UV/Vis spectra of the bilayer species are theoretically simulated to facilitate their future spectral characterizations.

Transition metal dichalcogenide (TMD) quantum dots (QDs) with defects have attracted interesting chemistry due to the contribution of vacancies to their unique optical, physical, catalytic, and electrical properties. Engineering defined defects into molybdenum sulfide (MoS2) QDs is challenging. Herein, by applying a mild biomineralization‐assisted bottom‐up strategy, blue photoluminescent MoS2 QDs (B‐QDs) with a high density of defects are fabricated. The two‐stage synthesis begins with a bottom‐up synthesis of original MoS2 QDs (O‐QDs) through chemical reactions of Mo and sulfide ions, followed by alkaline etching that creates high sulfur‐vacancy defects to eventually form B‐QDs. Alkaline etching significantly increases the photoluminescence (PL) and photo‐oxidation. An increase in defect density is shown to bring about increased active sites and decreased bandgap energy; which is further validated with density functional theory calculations. There is strengthened binding affinity between QDs and O2 due to lower gap energy (∆EST) between S1 and T1, accompanied with improved intersystem crossing (ISC) efficiency. Lowered gap energy contributes to assist e−–h+ pair formation and the strengthened binding affinity between QDs and 3O2. Defect engineering unravels another dimension of material properties control and can bring fresh new applications to otherwise well characterized TMD nanomaterials.

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