A highly active FeSe electrocatalyst for durable overall water splitting was prepared from a molecular 2Fe-2Se precursor. The as-synthesized FeSe was electrophoretically deposited on nickel foam and applied to the oxygen and hydrogen evolution reactions (OER and HER, respectively) in alkaline media. When used as an oxygen-evolution electrode, a low 245 mV overpotential was achieved at a current density of 10 mA cm , representing outstanding catalytic activity and stability because of Fe(OH) /FeOOH active sites formed at the surface of FeSe . Remarkably, the system is also favorable for the HER. Moreover, an overall water-splitting setup was fabricated using a two-electrode cell, which displayed a low cell voltage and high stability. In summary, the first iron selenide material is reported that can be used as a bifunctional electrocatalyst for the OER and HER, as well as overall water splitting.
'Black' TiO -in the widest sense, TiO reduced by various treatments-has attracted tremendous scientific interest in recent years because of some outstanding properties; most remarkably in photocatalysis. While the material effects visible light absorption (the blacker, the better), black titania produced by high pressure hydrogenation was recently reported to show another highly interesting feature; noble-metal-free photocatalytic H generation. In a systematic investigation of high-temperature hydrogen treatments of anatase nanoparticles, TEM, XRD, EPR, XPS, and photoelectrochemistry are used to characterize different degrees of surface hydrogenation, surface termination, electrical conductivity, and structural defects in the differently treated materials. The materials' intrinsic activity for photocatalytic hydrogen evolution is coupled neither with their visible light absorption behavior nor the formation of amorphous material, but rather must be ascribed to optimized and specific defect formation (gray is better than black). This finding is further confirmed by using a mesoporous anatase matrix as a hydrogenation precursor, which, after conversion to the gray state, even further enhances the overall photocatalytic hydrogen evolution activity.
The first β-diketiminato triphosphido diiron complex was synthesized as a versatile molecular single-source precursor for the production of functional FeP that acts as a powerful and durable bifunctional electrocatalyst for water splitting.
Recently, the use of a new family of electroluminescent copper(I) complexes—i.e., the archetypal [Cu(IPr)(3‐Medpa)][PF6] complex; IPr: 1,3‐bis‐(2,6‐di‐iso‐propylphenyl)imidazole‐2‐ylidene; 3‐Medpa: 2,2′‐bis‐(3‐methylpyridyl)amine—has led to blue light‐emitting electrochemical cells (LECs) featuring luminances of 20 cd m−2, stabilities of 4 mJ, and efficiencies of 0.17 cd A−1. Herein, this study rationalizes how to enhance these figures‐of‐merit optimizing both device fabrication and design. On one hand, a comprehensive spectroscopic and electrochemical study reveals the degradation of this novel emitter in common solvents used for LEC fabrication, as well as the impact on the photoluminescence features of thin‐films. On the other hand, spectro‐electrochemical and electrochemical impedance spectroscopy assays suggest that the device performance is strongly limited by the irreversible formation of oxidized species that mainly act as carrier trappers and luminance quenchers. Based on all of the aforementioned, device optimization was realized using ionic additives and a hole transporter either as a host–guest or as a multilayered architecture approach to decouple hole/electron injection. The latter significantly enhances the LEC performance, reaching luminances of 160 cd m−2, stabilities of 32.7 mJ, and efficiencies of 1.2 cd A−1. Overall, this work highlights the need of optimizing both device fabrication and design toward highly efficient and stable LECs based on cationic copper(I) complexes.
The utility of the bulky aryloxide ligands 2,6-Ad 2 -4-Me-C 6 H 2 O − ( Ad,Ad,Me ArO − ) and 2,6-Ad 2 -4-t-Bu-C 6 H 2 O − ( Ad,Ad,t-Bu ArO − ; Ad = 1-adamantyl) for stabilizing the Y(II) ion is reported and compared with the results with 2,6-t-Bu 2 -4-Me-C 6 H 2 O − (Ar′O − ). In contrast to the reduction product obtained from reducing Y(OAr′) 3 with potassium graphite, which is only stable in solution for 60 s at room temperature, KC 8 reduction of Y(OAr Ad,Ad,t-Bu ) 3 in THF in the presence of 2.2.2-cryptand (crypt) produces the room-temperature stable, crystallographically characterizable Y(II) aryloxide [K(crypt)]-[Y(OAr Ad,Ad,t-Bu ) 3 ]. The X-band EPR spectrum at 77 K shows an axial pattern with resonances centered at g ⊥ = 1.97 and g ∥ = 2.00 and hyperfine coupling constants of A ⊥ = 156.5 G and A ∥ = 147.8 G and at room temperature shows an isotropic pattern with g iso = 1.98 and A iso = 153.3 G, which is consistent with an S = 1/2 spin system with nuclear spin I = 1/2 for the 89 Y isotope (100% natural abundance).
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