Herein, we demonstrate the use of heterostructures comprised of Co/β‐Mo2C@N‐CNT hybrids for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline electrolyte. The Co can not only create a well‐defined heterointerface with β‐Mo2C but also overcomes the poor OER activity of β‐Mo2C, thus leading to enhanced electrocatalytic activity for HER and OER. DFT calculations further proved that cooperation between the N‐CNTs, Co, and β‐Mo2C results in lower energy barriers of intermediates and thus greatly enhances the HER and OER performance. This study not only provides a simple strategy for the construction of heterostructures with nonprecious metals, but also provides in‐depth insight into the HER and OER mechanism in alkaline solution.

Herein, we demonstrate the use of heterostructures comprised of Co/b-Mo 2 C@N-CNT hybrids for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline electrolyte.T he Co can not only create awell-defined heterointerface with b-Mo 2 Cbut also overcomes the poor OER activity of b-Mo 2 C, thus leading to enhanced electrocatalytic activity for HER and OER. DFT calculations further proved that cooperation between the N-CNTs,Co, and b-Mo 2 Cr esults in lower energy barriers of intermediates and thus greatly enhances the HER and OER performance.T his study not only provides asimple strategy for the construction of heterostructures with nonprecious metals,but also provides indepth insight into the HER and OER mechanism in alkaline solution.Electrochemical conversion of H 2 Oi nto hydrogen fuel (2 H 2 O!2H 2 + O 2 )h as attracted great attention from the scientific community because of its potential to replace fossil fuels. [1] Thee lectrolysis of water involves two half reactions: the cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER), for which highly efficient electrocatalysts,s uch as Pt for the HER and IrO 2 for the OER, are usually required. [2,3] However,t he low abundance and high cost of noble-metal catalysts significantly hinder their large-scale commercialization. [4] Therefore,i ti si mperative to develop highly efficient nonprecious bifunctional electrocatalysts for both the HER and OER using the same electrolyte. [5,6] Recently,m any earth-abundant, noble-metal-free catalysts for the half-cell reactions have been explored as potential substitutes.S pecifically,t ransition-metal-based carbides, [7] sulfides, [8] phosphides, [9] and selenides [10] exhibit optimum catalytic performance for the HER, and it has been established that molybdenum carbide (Mo 2 C) has excellent HER activity in both acidic and basic electrolytes because the d-band electronic structure of Mo is similar to that of the noble metal Pt. [11][12][13] Notably,t he combination of Mo 2 Cw ith transition metals can effectively reduce the amount of unoccupied dorbitals of Mo to further enhance the HER activity,o wing to the electron-rich nature of transition metals.A lthough Mo 2 C-based materials with superior HER properties have been widely reported, their low OER activity has become am ajor obstacle for overall water splitting.T od ate,t he investigation of Mo 2 C-based electrocatalysts for OER has been limited. In this context, Yu and co-workers synthesized Ni/Mo 2 Cn anorods coated with apolydopamine hybrid, which required an overpotential (h 10 ) of over 368 mV to reach ac urrent density of 10 mA cm À2 , [14] and Luo and co-workers reported aMo 2 C/carbon hybrid that required an h 10 value over 500 mV. [15] Thea bove results suggest that the development of an efficient Mo 2 C-based electrocatalyst to create aw ater electrolyzer is still ac onsiderable challenge. [16] Cobalt-based hybrids can greatly improve the OER catalytic activity of materials,i ncluding Co-N, [17] Co-...

The highly active and stable oxygen evolution reaction (OER) performance of Ni–Fe phosphide/metaphosphate (Ni1−xFex-P/PO3) can originate from in situ generated Fe doped γ-NiOOH.

Photoelectrocatalytic (PEC) CO2 reduction to value-added chemicals is a promising solution to address the energy and environmental issues we face currently. Herein, a unique photocathode Bi@ZFO NTs (Bi and α-Fe2O3 co-modified ZnO nanorod arrays) with high utilization of visible light and sharp-tips effect are successfully prepared using a facile method. Impressively, the performance of Bi@ZFO NTs for PEC CO2 reduction to HCOOH included small onset potential (−0.53 V vs RHE), Tafel slope (101.2 mV dec–1), and a high faraday efficiency of 61.2% at −0.65 V vs RHE as well as favorable stability over 4 h in an aqueous system under visible light illumination. Also, a series of experiments were performed to investigate the origin of its high activity, indicating that the metallic Bi and α-Fe2O3/ZnO nanojunction should be responsible for the favorable CO2 adsorption/activation and charge transition/carrier separation, respectively. Density functional theory calculations reveal that the Bi@ZFO NTs could lower the intermediates’ energy barrier of HCOO* and HCOOH* to form HCOOH due to the strong interaction of Bi and α-Fe2O3/ZnO.

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Circular-side square microlasers with shifted output waveguide positions are demonstrated to realize mode and lasing spectrum control. Numerical simulation results indicate that the mode Q factors of the fundamental, first- and second-order transverse modes are modulated, and the output coupling efficiency of the output waveguide can be greatly improved by introducing the translation of the output waveguide. Single-mode lasing, dual-mode lasing, and three-mode lasing are experimentally realized by changing the output waveguide positions. At the optimized shifted output waveguide position, a microlaser exhibits tunable single-mode behavior with a maximum output power of 120 µW, a side-mode suppression ratio of 31 dB, and a linewidth of 42 MHz. Furthermore, the lasing characteristics of microlasers with different circular sides are compared.

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