Electronic Perturbation of Isolated Fe Coordination Structure for Enhanced Nitrogen Fixation.

Modulation of the local electronic structure of isolated coordination structures plays a critical role in electrocatalysis yet remains a grand challenge. Herein, we have achieved electron perturbation for the isolated iron coordination structure via tuning the iron spin state from a high spin state (FeN4) to a medium state (FeN2B2). The transition of spin polarization facilitates electron penetration into the antibonding π orbitals of nitrogen and effectively activates nitrogen molecules, thereby achieving an ammonia yield of 115 µg h-1 mg-1cat. and a Faradaic efficiency of 24.8%. In situ spectroscopic studies and theoretical calculations indicate that boron coordinate sites, as electron acceptors, can regulate the adsorption energy of NxHy intermediates on the Fe center. FeN2B2 sites favor the NNH* intermediate formation and reduce the energy barrier of rate-determining steps, thus accounting for excellent nitrogen fixation performance. Our strategy provides an effective approach for designing efficient electrocatalysts via precise electronic perturbation.

Correlating Structural Disorder in Metal (Oxy)hydroxides and Catalytic Activity in Electrocatalytic Oxygen Evolution.

Understanding the correlation between the structural evolution of electrocatalysts and their catalytic activity is both essential and challenging. In this study, we investigate this correlation in the context of the oxygen evolution reaction (OER) by examining the influence of structural disorder during and after dynamic structural evolution on the OER activity of Fe-Ni (oxy)hydroxide catalysts using operando X-ray absorption spectroscopy, alongside other experiments and theoretical calculations. The Debye-Waller factors obtained from extended X-ray absorption fine structure analyses reflect the degree of structural disorder and exhibit a robust correlation with the intrinsic OER activities of the electrocatalysts. The enhanced OER activity of in situ-generated metal (oxy)hydroxides derived from different pre-catalysts is linked to increased structural disorder, offering a promising approach for designing efficient OER electrocatalysts. This strategy may inspire similar investigations in related electrocatalytic energy-conversion systems.

Isolated Electron Trap-Induced Charge Accumulation for Efficient Photocatalytic Hydrogen Production.

The solar-driven evolution of hydrogen from water using particulate photocatalysts is considered one of the most economical and promising protocols for achieving a stable supply of renewable energy. However, the efficiency of photocatalytic water splitting is far from satisfactory due to the sluggish electron-hole pair separation kinetics. Herein, isolated Mo atoms in a high oxidation state have been incorporated into the lattice of Cd0.5 Zn0.5 S (CZS@Mo) nanorods, which exhibit photocatalytic hydrogen evolution rate of 11.32 mmol g-1 h-1 (226.4 µmol h-1 ; catalyst dosage 20 mg). Experimental and theoretical simulation results imply that the highly oxidized Mo species lead to mobile-charge imbalances in CZS and induce the directional photogenerated electrons transfer, resulting in effectively inhibited electron-hole recombination and greatly enhanced photocatalytic efficiency.

Direct Utilization of Photoinduced Charge Carriers to Promote Electrochemical Energy Storage.

Electrochemical energy storage has been regarded as one of the most promising strategies for next-generation energy consumption. To meet the increasing demands of urban electric vehicles, development of green and efficient charging technologies by exploitation of solar energy should be considered for outdoor charging in the future. Herein, a light-sensitive material (copper foam-supported copper oxide/nickel copper oxides nanosheets arrays, namely CF@CuOx @NiCuOx NAs) with hierarchical nanostructures to promote electrochemical charge storage is specifically fabricated. The as-fabricated NAs have demonstrated a high areal specific capacity of 1.452 C cm-2 under light irradiation with a light power of 1.76 W, which is 44.8% higher than the capacity obtained without light. Such areal specific capacity (1.452 C cm-2 ) is much higher than that of the conventional supercapacitor structure using a similar active redox component reported recently (NiO nanosheets array@Co3 O4 -NiO FTNs: maximum areal capacity of 623.5 mF cm-2 at 2 mA cm-2 ). This photo-enhancement for charge storage can be attributed to the combination of photo-sensitive Cu2 O and pseudo-active NiO components. Hence, this work may provide new possibilities for direct utilization of sustainable solar energy to realize enhanced capability for energy storage devices.

Fabrication of Core-Shell Nanocolloids with Various Core Sizes to Promote Light Capture for Green Fuels.

Core-shell nanocolloids with tailored physical and chemical merits hold attractive potential for energy-related applications. Herein, core-shell nanocolloids composed of zinc/copper sulfide (ZnS/CuSx ) shells and silica (SiO2 ) cores were fabricated by a template-engaged synthetic method. Interestingly, the sizes of SiO2 cores can be tuned by different sulfurization time. In virtue of the light scattering and reflection on the SiO2 surface, the efficiencies of light capture by ZnS/Cu2 S shells were highly dependent on the SiO2 sizes. The as-fabricated SiO2 @ZnS/Cu2 S with a core size of 205 nm exhibited the highest and broadest absorption within a light wavelength of 380-700 nm. In virtue of the structural and componential features of these nanocolloids, maximum photocatalytic hydrogen (H2 ) production rates of 2968 and 1824 µmol h-1 g-1 under UV-vis and visible light have been delivered, respectively. This work may provide some evidence for the design and fabrication of core-shell nanomaterials to convert solar energy to green fuels.