Cobalt-based nanomaterials have been intensively explored as promising noble-metal-free oxygen evolution reaction (OER) electrocatalysts. Herein, we report phase-selective syntheses of novel hierarchical CoTe and CoTe nanofleeces for efficient OER catalysts. The CoTe nanofleeces exhibited excellent electrocatalytic activity and stablity for OER in alkaline media. The CoTe catalyst exhibited superior OER activity compared to the CoTe catalyst, which is comparable to the state-of-the-art RuO catalyst. Density functional theory calculations showed that the binding strength and lateral interaction of the reaction intermediates on CoTe and CoTe are essential for determining the overpotential required under different conditions. This study provides valuable insights for the rational design of noble-metal-free OER catalysts with high performance and low cost by use of Co-based chalcogenides.

Photocatalysis of a single methanol molecule on the TiO 2 (110) surface was investigated using a high-resolution scanning tunneling microscopy (STM) technique. Three different types of elementary methanol photocatalytic processes, methanol photodissociation, photoinduced migration of formaldehyde, and formaldehyde photodesorption, were clearly observed. Detailed chemical structures of the intermediates were obtained through careful comparisons between experimental STM images and theoretical simulations based on density functional theory (DFT) calculations. This work demonstrates that elementary photocatalytic processes of a single methanol molecule on the surface can be followed step by step using advanced STM imaging techniques. Such a study can provide unprecedented insights into the surface photocatalytic processes and will greatly help us to understand photocatalysis at the most fundamental level. ■ INTRODUCTIONSince water splitting was first demonstrated in a photoelectrochemical cell in the early 1970s, 1 photocatalysis on TiO 2 has received extensive and increasing attention because of its potential applications in clean hydrogen production. 2−6 Despite enormous progress made in this area, a fundamental understanding of heterogeneous photocatalysis is still lacking. It is known that TiO 2 alone was found not very active for water splitting to produce hydrogen, whereas adding methanol would dramatically enhance hydrogen production. 7 In order to apprehend the role of methanol in the photocatalysis of water on TiO 2 , it is essential to investigate methanol photocatalysis on TiO 2 at the atomic and molecular level. This will help us to understand the underlying mechanism of why TiO 2 is inactive for water splitting and why methanol can enhance hydrogen production.Methanol photocatalysis has been studied on TiO 2 single crystalline surfaces as well as on supported nanoparticles using various spectroscopic techniques. 8−15 It was generally believed that under the UV-light irradiation methanol dehydrogenates sequentially to formaldehyde, which could desorb or go through further cross coupling with another methoxy radical to form methyl formate. Even though these studies have provided valuable insights into the methanol photocatalysis mechanism, the detailed picture of how a single methanol molecule on TiO 2 evolves into the final products under light irradiation remains unclear.Scanning tunneling microscope (STM) studies with submolecular resolution can provide detailed structural information on reaction intermediates on surfaces. 16−20 The STM technique with submolecular resolution coupled with light irradiation is also expected to be a good approach to directly image molecular photocatalysis. The TiO 2 (110) surface has been studied in great detail using the STM technique. 21−30 The clear STM image of the surface structure provides a solid foundation for us to investigate single methanol molecule photocatalysis on the TiO 2 (110) surface. However, to directly image the molecular photocatalysis step by step is...

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Ammonia (NH 3 ) is an essential nitrogen feedstock for fertilizer and efficient energy carrier. [1,2] The traditional process for synthesizing NH 3 is mostly produced via the Haber-Bosch process. [3] Up to now, the well-established Haber-Bosch process Electrocatalysts for efficient production of ammonia from nitrogen reduction reaction (NRR) under ambient conditions are attracted growing interest in recent years, which demonstrate a great potential to replace the Haber-Bosch method which suffers the problems of the huge energy consumption and massive CO 2 production. In this work, a novel electrocatalyst of Au 25 -Cys-M is fabricated for NRR under ambient conditions, with transition metal ions (e.g., Mo 6+ , Fe 3+ , Co 2+ , Ni 2+ ) atomically decorated on Au 25 nanoclusters via thiol bridging. The Au 25 -Cys-Mo catalyst exhibits the highest Faradaic efficiency (26.5%) and NH 3 yield (34.5 µg h −1 mg cat −1 ) in 0.1 m HCl solution. X-ray photoelectron spectroscopy analysis and high angle annular dark field imagescanning transmission electron microscopy characterization reveal that the electronic structure of Mo is optimized by forming the structure of Au-S-Mo and Mo acts as active sites for activating the nitrogen to promote the electrochemical production of ammonia. This work provides a new insight into the precise fabrication of efficient NRR electrocatalysts.

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Cobalt‐based nanomaterials have been intensively explored as promising noble‐metal‐free oxygen evolution reaction (OER) electrocatalysts. Herein, we report phase‐selective syntheses of novel hierarchical CoTe2 and CoTe nanofleeces for efficient OER catalysts. The CoTe2 nanofleeces exhibited excellent electrocatalytic activity and stablity for OER in alkaline media. The CoTe2 catalyst exhibited superior OER activity compared to the CoTe catalyst, which is comparable to the state‐of‐the‐art RuO2 catalyst. Density functional theory calculations showed that the binding strength and lateral interaction of the reaction intermediates on CoTe2 and CoTe are essential for determining the overpotential required under different conditions. This study provides valuable insights for the rational design of noble‐metal‐free OER catalysts with high performance and low cost by use of Co‐based chalcogenides.