Synthesis of supported Pd nanocluster catalyst by spontaneous reduction on layered double hydroxide

Surface-Confined Ultra-Low Scale Pd Engineered Layered Co(OH)2 toward High-Performance Hydrazine Electrooxidation in Alkaline Saline Water

Applications of abundant seawater in electrochemical energy conversion are constrained due to the sluggish oxygen evolution reaction and the corrosive chlorine oxidation reaction. Hence, it is imperative to develop an efficient anodic reaction alternative suitable for coupling with the cathodic counterpart. Due to a low thermodynamic oxidation potential, hydrazine oxidation reaction (HzOR) offers a unique pathway to overcome these challenges. Herein, spontaneously in situ reduced atomic scale Pd surface-confined to electrochemically prepared layered Co(OH)2 on carbon cloth is synthesized. This study reveals the hydrazine and Pd-dependent morphological evolution of Co(OH)2 and its Pd hybrids into nanoparticulate form. Unlike various layered double hydroxides, Pd integrated Co(OH)2 benefits from the contribution of Co(OH)2 as an active HzOR catalyst and the reductive support to host Pd, resulting in synergistically improved performances. Mass activities of Pd in alkaline and alkaline saline electrolyte are 11.24 and 9.83 A mgPd -1 at 200 mV, respectively, corresponding to the highest HzOR activities among noble metals. The optimized Pd hybrid demonstrates ≈6.5 times the current density relative to PtC (14.91 mA cm-2 at 200 mV) in alkaline saline water with hydrazine. These findings would be beneficial to realize high overpotential anodic alternatives and reduce over-dependence on freshwater for electrocatalysis.

Hybrid monometallic and bimetallic copper-palladium zeolite catalysts for direct synthesis of dimethyl ether from CO2

Nowadays, carbon dioxide is the major reason of the global climate changes. The direct CO2 hydrogenation to dimethyl ether produces an important platform molecule for synthesis of fuels and chemicals...

High-Loading, Well-Dispersed Phosphorus Confined on Nanoporous Carbon Surfaces with Enhanced Catalytic Activity and Cyclic Stability

Phosphorus-doped carbon materials are promising alternatives to noble metal-based catalysts for the highly selective oxidation of benzyl alcohol to benzaldehyde, but it is challenging to achieve high loadings of high-activity P dopants in metal-free catalysts. Here, the preparation of high-loading and well-dispersed P atoms confined to the surfaces of cellulose-derived carbon via a dissolving-doping strategy is reported. In this method, cellulose is dissolved in phosphoric acid to generate a cellulose-phosphoric supramolecular collosol, which is then directly carbonized. The as-prepared carbon possesses a high specific surface area of 1491 cm³ g^-1 and a high P content of 8.8 wt%. The P-doped nanoporous carbon shows a superior catalytic activity and cyclic stability toward benzyl alcohol oxidation, with a high turnover frequency of 3.5 × 10^-3 mol g^-1 h^-1 and a low activation energy of 35.6 kJ mol^-1 . Experimental results and theoretical calculations demonstrate that the graphitic C₃ PO species is the leading catalytic active center in this material. This study provides a novel strategy to prepare P dopants in nanoporous carbon materials with excellent catalytic performance.

Oxygenated functional group-driven spontaneous fabrication of Pd nanoparticles decorated porous carbon nanosheets for electrocatalytic hydrodechlorination of 4-chlorophenol

Researchers have been committed to reducing the hazardous pollutants by developing efficient catalysts while ignoring the pollution caused by the use of toxic surface capping agents, reductants and/or organic solvents in the catalyst preparation process. To alleviate such problems, we here report a novel one-step oxygenated functional group-driven electroless deposition strategy to synthesize clean and uniformly distributed Pd nanoparticles (NPs) using porous carbon nanosheets (PCN) as both substrates and reducing agents. It is observed that the oxygenated functional groups enriched PCN possesses a low work function and allows the spontaneous reduction of PdCl₄^2- ions to Pd NPs deposited on the PCN support (Pd/PCN). The particle size of Pd NPs can be flexibly modulated by simply controlling the immersing time and thereby their maximum catalytic performances can be achieved. Specifically, the optimal Pd/PCN-08 with a Pd loading of 3.0 wt% shows an excellent activity with a turnover frequency of 0.38 min^-1 for electrocatalytic hydrodechlorination (ECH) of 4-chlorophenol (4-CP), superior to the previously reported materials. The stability of Pd/PCN-08 for 4-CP ECH is impressive in repetitive cycles. This work proposes a facile and efficient strategy to synthesize high-performance catalysts for detoxifying the hazardous organic pollutants.

In situ construction of sulfated TiO2 nanoparticles with TiOSO4 for enhanced photocatalytic hydrogen production

Photocatalytic hydrogen production from water is a promising method to obtain clean energy in the future. In this work, the sulfated TiO2 photocatalyst is successfully constructed in situ via a soft-templated method for photocatalytic water splitting to produce hydrogen. The content of sulfate species in TiO2 can be tuned by changing the amount of the surfactant. The photocatalyst with the appropriate content of sulfate ions exhibits an apparent quantum efficiency (AQE) of 3.9% at 365 nm and a high hydrogen production rate of 24.32 mmol h-1 g-1, which is 1.65 times that of commercial TiO2 (P25). The optimized photocatalyst has excellent photocatalytic activity for hydrogen evolution benefitting from the presence of sulfate ions on the surface of TiO2, large surface area and oxygen vacancies, which facilitates the rapid migration of photo-generated electrons to its surface and the improvement of the separation efficiency of photo-generated carriers. This work may inspire the rational design and the development of high-efficiency photocatalysts.