Hydride-containing 2-Electron Pd/Cu Superatoms as Catalysts for Efficient Electrochemical Hydrogen Evolution

The first hydride-containing 2-electron palladium/copper alloys, [PdHCu₁₁{S₂P(OⁱPr)₂}₆(C≡CPh)₄] ( PdHCu₁₁ ) and [PdHCu₁₂{S₂P(OⁱPr)₂}₅{S₂PO(OⁱPr)} (C≡CPh)₄] ( PdHCu₁₂ ), are synthesized from the reaction of [PdH₂Cu₁₄{S₂P(OⁱPr)₂}₆(C≡CPh)₆] ( PdH₂Cu₁₄ ) with trifluoroacetic acid (TFA). X-ray diffraction reveals that the PdHCu₁₁ and PdHCu₁₂ kernels consist of a central PdH unit encapsulated within a vertex-missing Cu₁₁ cuboctahedron and complete Cu₁₂ cuboctahedron, respectively. DFT calculations indicate that both PdHCu₁₁ and PdHCu₁₂ can be considered as axially-distorted 2-electron superatoms. PdHCu₁₁ shows excellent HER activity, unprecedented within metal nanoclusters, with an onset potential of −0.05 V (at 10 mA cm⁻²), a Tafel slope of 40 mV dec⁻¹, and consistent HER activity during 1000 cycles in 0.5 M H₂SO₄. Our study suggests that the accessible central Pd site is the key to HER activity and may provide guidelines for correlating catalyst structures and HER activity.     

Enhancing Built-in Electric Fields for Efficient Photocatalytic Hydrogen Evolution by Encapsulating C60 Fullerene into Zirconium-Based Metal-Organic Frameworks

High-efficiency photocatalysts based on metal-organic frameworks (MOFs) are often limited by poor charge separation and slow charge-transfer kinetics. Herein, a novel MOF photocatalyst is successfully constructed by encapsulating C₆₀ into a nano-sized zirconium-based MOF, NU-901. By virtue of host-guest interactions and uneven charge distribution, a substantial electrostatic potential difference is set-up in C₆₀@NU-901. The direct consequence is a robust built-in electric field, which tends to be 10.7 times higher in C₆₀@NU-901 than that found in NU-901. In the catalyst, photogenerated charge carriers are efficiently separated and transported to the surface. For example, photocatalytic hydrogen evolution reaches 22.3 mmol g⁻¹ h⁻¹ for C₆₀@NU-901, which is among the highest values for MOFs. Our concept of enhancing charge separation by harnessing host-guest interactions constitutes a promising strategy to design photocatalysts for efficient solar-to-chemical energy conversion.     

New Radical Route and Insight for the Highly Efficient Synthesis of Benzimidazoles Integrated with Hydrogen Evolution

Benzimidazoles are a versatile class of scaffolds with important biological activities, whereas their synthesis in a lower-cost and more efficient manner remains a challenge. Here, we demonstrate a conceptually new radical route for the high-performance photoredox coupling of alcohols and diamines to synthesize benzimidazoles along with stoichiometric hydrogen (H₂) over Pd-decorated ultrathin ZnO nanosheets (Pd/ZnO NSs). The mechanistic study reveals the unique advantage of ZnO NSs over other supports and particularly that the features of Pd nanoparticles in facilitating the cleavage of the α-C−H bond of alcohols and adsorbing subsequently-generated C-centered radicals hold the key to turning on the reaction. This work highlights a new insight into radical-induced efficient benzimidazole synthesis pairing with H₂ evolution by rationally designing semiconductor-based photoredox systems.     

Intermediate Formation of Macrocycles for Efficient Crystallization of 2D Covalent Organic Frameworks with Enhanced Photocatalytic Hydrogen Evolution

Covalent organic frameworks (COFs) have gained significant attention as key photocatalysts for efficient solar light conversion into hydrogen production. Unfortunately, the harsh synthetic conditions and intricate growth process required to obtain highly crystalline COFs greatly hinder their practical application. Herein, we report a simple strategy for the efficient crystallization of 2D COFs based on the intermediate formation of hexagonal macrocycles. Mechanistic investigation suggests that the use of 2,4,6-triformyl resorcinol (TFR) as the asymmetrical aldehyde build block allows the equilibration between irreversible enol-to-keto tautomerization and dynamic imine bonds to produce the hexagonal β-ketoenamine-linked macrocycles, the formation of which could provide COFs with high crystallinity in half hour. We show that COF-935 with 3 wt % Pt as cocatalyst exhibit a high hydrogen evolution rate of 67.55 mmol g⁻¹ h⁻¹ for water splitting when exposed to visible light. More importantly, COF-935 exhibits an average hydrogen evolution rate of 19.80 mmol g⁻¹ h⁻¹ even at a low loading of only 0.1 wt % Pt, which is a significant breakthrough in this field. This strategy would provide valuable insights into the design of highly crystalline COFs as efficient organic semiconductor photocatalysts.     

Ru Nanoparticles Supported on Co-Embedded N-Doped Carbon Nanotubes as Efficient Electrocatalysts for Hydrogen Evolution in Basic Media

A challenging but urgent task is to construct efficient and robust hydrogen evolution reaction(HER) electrocatalysts for practically feasible and sustainable hydrogen production through alkaline water electrolysis. Herein we report a simple and mild pyrolysis method to synthesize the efficient Ru nanoparticles(NPs) supported on Co-embedded N-doped carbon nanotubes(Ru/Co-NCNTs) catalyst for HER in basic media. The Ru/Co-NCNTs display remarkable performance with a low overpotential of only 35 mV at 10 mA/cm², a small Tafel slope(36 mV/dec), and a high mass activity in 1 mol/L KOH, which is superior to commercial 20% Pt/C catalyst. This excellent performance is benefited from the enhanced conductivity of N-doped carbon nanotubes(NCNTs) and high intrinsic activity triggered by synergistic coupling between Ru NPs and Co-embedded N-doped carbon nanotubes(Co-NCNTs).     

Microwave Synthesis of Pt Clusters on Black TiO2 with Abundant Oxygen Vacancies for Efficient Acidic Electrocatalytic Hydrogen Evolution

Oxygen vacancies-enriched black TiO₂ is one promising support for enhancing hydrogen evolution reaction (HER). Herein, oxygen vacancies enriched black TiO₂ supported sub-nanometer Pt clusters (Pt/TiO₂-O_V) with metal support interactions is designed through solvent-free microwave and following low-temperature electroless approach for the first time. High-temperature and strong reductants are not required and then can avoid the aggregation of decorated Pt species. Experimental and theoretical calculation verify that the created oxygen vacancies and Pt clusters exhibit synergistic effects for optimizing the reaction kinetics. Based on it, Pt/TiO₂-O_V presents remarkable electrocatalytic performance with 18 mV to achieve 10 mA cm⁻² coupled with small Tafel slope of 12 mV dec⁻¹. This work provides quick synthetic strategy for preparing black titanium dioxide based nanomaterials.     

Hierarchical Architectures Based on Ru Nanoparticles/Oxygen-Rich-Carbon Nanotubes for Efficient Hydrogen Evolution

Highly active and durable electrocatalysts are essential for producing hydrogen fuel through the hydrogen evolution reaction (HER). Here, a uniform deposition of Ru nanoparticles strongly interacting with oxygen-rich carbon nanotube architectures (Ru-OCNT) through ozonation and hydrothermal approaches has been designed. The hierarchical structure of Ru-OCNT is made by self-assembly of oxygen functionalities of OCNT. Ru nanoparticles interact strongly with OCNT at the Ru/OCNT interface to give excellent catalytic activity and stability of the Ru-OCNT, as further confirmed by density functional theory. Owing to the hierarchical structure and adjusted surface chemistry, Ru-OCNT has an overpotential of 34 mV at 10 mA cm⁻² with a Tafel slope of 27.8 mV dec⁻¹ in 1 M KOH, and an overpotential of 55 mV with Tafel slope of 33 mV dec⁻¹ in 0.5 M H₂SO₄. The smaller Tafel slope of Ru-OCNT than Ru-CNT and commercial Pt/C in both alkaline and acidic electrolytes indicates high catalytic activity and fast charge transfer kinetics. The as-proposed chemistry provides the rational design of hierarchically structured CNT/nanoparticle electrocatalysts for HER to produce hydrogen fuel.     

Engineering a Self-Grown TiO2/Ti-MOF Heterojunction with Selectively Anchored High-Density Pt Single-Atomic Cocatalysts for Efficient Visible-Light-Driven Hydrogen Evolution

A photocatalyst TiO₂/Ti-BPDC-Pt is developed with a self-grown TiO₂/Ti-metal–organic framework (MOF) heterojunction, i.e., TiO₂/Ti-BPDC, and selectively anchored high-density Pt single-atomic cocatalysts on Ti-BPDC for photocatalytic hydrogen evolution. This intimate heterojunction, growing from the surface pyrolytic reconstruction of Ti-BPDC, works in a direct Z-scheme, efficiently separating electrons and holes. Pt is selectively anchored on Ti-BPDC by ligands and is found in the form of single atoms with loading up to 1.8 wt %. The selective location of Pt is the electron-enriched domain of the heterojunction, which further enhances the utilization of the separated electrons. This tailored TiO₂/Ti-BPDC-Pt shows a significantly enhanced activity of 12.4 mmol g⁻¹ h⁻¹ compared to other TiO₂- or MOF-based catalysts. The structure-activity relationship further proves the balance of two simultaneously exposed domains of heterojunctions is critical to fulfilling this kind of catalyst.     

Copper-linked 1T MoS2/Cu2O Heterostructure for Efficient Photocatalytic Hydrogen Evolution

Metallic 1T phase molybdenum disulfide(1T MoS₂) is an excellent catalyst due to the abundant active sites and good conductivity. However, complex synthesis and unstable nature of 1T MoS₂ still limit its practical application. Herein, we propose a simple method to trigger the phase transition of MoS₂. This phase transition is first predicted by density functional theory(DFT) calculations and then confirmed by Raman spectroscopy and high-resolution transmission electron microscopy(HRTEM). 1T MoS₂/Cu₂O heterostructure catalyst is then developed, showing enhanced photocatalytic hydrogen evolution.     

An Efficient RuTe2/Graphene Catalyst for Electrochemical Hydrogen Evolution Reaction in Acid Electrolyte

Developing efficient powder catalysts for hydrogen evolution reaction (HER) in the acidic electrolyte is significant for hydrogen generation in the proton exchange membrane (PEM) water electrolysis technique. Herein, we demonstrated an efficient catalyst for HER in the acid media based on the graphene supported ruthenium telluride nanoparticles (RuTe₂/Gr). The catalysts were easily fabricated by a facile microwave irradiation/thermal annealing approach, and orthorhombic RuTe₂ crystals were found anchored over the graphene surface. The defective structure was demonstrated in the aberration‐corrected transmission electron microscopy images for RuTe₂ crystals and graphene support. This catalyst required an overpotential of 72 mV to drive 10 mA cm^?2 for HER when loading on the inert glass carbon electrode; Excellent catalytic stability in acidic media was also observed to offer 10 mA cm^?2 for 10 hours. The Volmer‐Tafel mechanism was indicated on RuTe₂/Gr catalyst by Tafel slope of 33 mV dec^?1, similar to that of Pt/C catalysts. The high catalytic performance of RuTe₂/Gr could be attributed to its high dispersion on the graphene surface, high electrical conductivity and low charge transfer resistance. This powder catalyst has potential application in the PEM water electrolysis technique because of its low cost and high stability.     

无定型钼硫化物/还原氧化石墨烯的辐射合成及其电催化析氢性能

钼硫化物被认为是一种高效的电催化析氢反应的催化剂,因此其合成方法受到了广泛的研究和关注。本文以四硫代钼酸铵和氧化石墨为前驱体,利用γ射线对其辐照还原,一步法制备了钼硫化物/还原氧化石墨烯(Mo S_x/RGO)复合材料。通过X射线光电子能谱、X射线衍射、透射电子显微镜、Raman光谱等表征手段确认复合材料中的Mo Sx为无定型结构,且氧化石墨烯得到了有效的还原。同时系统研究了吸收剂量、前驱体配比对复合材料作为析氢反应催化剂性能的影响。结果发现,Mo Sx/RGO复合材料具有优异的催化性能,其催化起始电压为110 m V,在电流密度为10 m A·cm~(-2)时过电势仅为160 m V,Tafel斜率为46 m V·dec~(-1),说明该催化剂催化析氢机理为Volmer-Heyrovesy机理。此外,Mo Sx/RGO复合材料还具有良好的催化稳定性。     

Dual MOF-Derived MoS2/CdS Photocatalysts with Rich Sulfur Vacancies for Efficient Hydrogen Evolution Reaction

Cocatalyst plays an important role in efficient charge transfer and separation for photocatalysis. Herein, a MoS₂/CdS photocatalyst with MoS₂ as cocatalyst was designed by using Mo-MOF and Cd-MOF as precursors. Due to the existence of rich sulfur vacancies and 1T phase, MoS₂ shows strong charge capture and transport ability. The photo-generated electrons on conduction band (CB) can be bound by the sulfur vacancy of CdS and effectively transported to MoS₂ through the compact interface between the CdS nanoparticles and 2D large-scale MoS₂. The optimal photocatalyst 1 %MoS₂/CdS exhibited dramatically improved photocatalytic hydrogen production activity, which is 28 times that of pristine CdS and even about 2 times that of 1 %Pt/CdS with same loading amount of noble metal Pt. This work highlights the role of Mo-MOF derived MoS₂ with 1T-2H phases as a sustainable and prospective candidate of cocatalyst for improving charge separation and photocatalytic stability of MoS₂/CdS composites.     

A Novel Electrochemical Method for the Analysis of Hydrogen Peroxide with the Use of a Glassy Carbon Electrode Modified by a Prussian Blue/Copper‐Gold Bimetallic Nanoparticles Hybrid Film

A novel Prussian blue/copper‐gold bimetallic nanoparticles hybrid film modified electrode was prepared by electrochemical deposition on a glassy carbon electrode (PB/Cu‐AuNPs/GCE). Morphology and electrochemistry of this electrode were studied by UV‐vis spectroscopy, scanning electron microscopy, X‐ray diffraction, cyclic voltammetry and electrochemical impedance spectroscopy. The sensor showed significantly better electrocatalytic activity for the reduction of hydrogen peroxide in comparison with the single PB/GCE and PB/AuNPs/GCE. This was attributed to the synergistic effect of PB and Cu‐Au bimetallic nanoparticles. Also, the sensor demonstrated an overall high level of performance for the analysis of H₂O₂ in the concentration range from 0.002 to 0.84 mM.