Caili Xu

Facile synthesis of effective Ru nanoparticles on carbon by adsorption-low temperature pyrolysis strategy for hydrogen evolution

The facile synthesis of efficient catalysts for hydrogen evolution from electrochemical water splitting and ammonia borane (AB) hydrolysis is highly important. Here, we develop an adsorption-low temperature pyrolysis method for facilely preparing uniformly dispersed Ru nanoparticles on carbon (Ru/C) with an outstanding catalytic property toward hydrogen generation from both electrochemical water splitting and AB hydrolysis. The experimental results indicate that the Ru/C synthesized by calcination at 300 °C (Ru/C-300) exhibits the highest catalytic activity for the hydrogen evolution reaction (HER) in basic solution, which requires an overpotential of only 14 mV at 10 mA cm−2. Additionally, this catalyst also displays high activity and reusability toward hydrogen evolution through AB hydrolysis, leading to a high turnover frequency of 643 mol H2 (min molRu)−1. Moreover, the Ru/C-300 shows excellent stability and reusability for both reactions. The adsorption-low temperature calcination strategy ensures that the small Ru nanoparticles are confined onto the carbon matrix, which can provide abundant highly reactive surface sites. It is discovered that the excellent catalytic activity of Ru/C depends largely on the size and dispersion of Ru nanoparticles as well as on their chemical states. This work may provide a facile and environmentally friendly strategy for preparing uniformly distributed metal nanocatalysts with high catalytic efficiencies for HER and AB hydrolysis.

In Situ Formation of AgCo Stabilized on Graphitic Carbon Nitride and Concomitant Hydrolysis of Ammonia Borane to Hydrogen

The development of highly-efficient heterogeneous supported catalysts for catalytic hydrolysis of ammonia borane to yield hydrogen is of significant importance considering the versatile usages of hydrogen. Herein, we reported the in situ synthesis of AgCo bimetallic nanoparticles supported on g-C3N4 and concomitant hydrolysis of ammonia borane for hydrogen evolution at room temperature. The as-synthesized Ag0.1Co0.9/g-C3N4 catalysts displayed the highest turnover frequency (TOF) value of 249.02 mol H2·(molAg·min)−1 for hydrogen evolution from the hydrolysis of ammonia borane, which was higher than many other reported values. Furthermore, the Ag0.1Co0.9/g-C3N4 catalyst could be recycled during five consecutive runs. The study proves that Ag0.1Co0.9/g-C3N4 is a potential catalytic material toward the hydrolysis of ammonia borane for hydrogen production.

Size and Electronic Modulation of Iridium Nanoparticles on Nitrogen Functionalized Carbon toward Advanced Electrocatalysts for Alkaline Water Splitting

Developing efficient catalytic materials for electrochemical water splitting is important. Herein, uniformly dispersed and size-controllable iridium (Ir) nanoparticles (NPs) were prepared using a nitrogen-functionalized carbon as the support (Ir/CN). We found that nitrogen functionalization can simultaneously modulate the size of Ir NPs to substantially enhance the catalytically active sites and adjust the electronic structure of Ir, thereby promoting electrocatalytic activity for water splitting. Consequently, the as-synthesized Ir/CN shows excellent electrocatalytic performance with overpotentials of 12 and 265 mV for hydrogen and oxygen evolution reactions in basic medium, respectively. These findings may pave the way for designing and synthesizing other similar materials as efficient catalysts for electrochemical water splitting.

Palladium Supported on Titanium Carbide: A Highly Efficient, Durable, and Recyclable Bifunctional Catalyst for the Transformation of 4-Chlorophenol and 4-Nitrophenol

Developing highly efficient and recyclable catalysts for the transformation of toxic organic contaminates still remains a challenge. Herein, Titanium Carbide (Ti3C2) MXene modified by alkali treatment process was selected as a support (designated as alk-Ti3C2X2, where X represents the surface terminations) for the synthesis of Pd/alk-Ti3C2X2. Results show that the alkali treatment leads to the increase of surface area and surface oxygen-containing groups of Ti3C2X2, thereby facilitating the dispersion and stabilization of Pd species on the surface of alk-Ti3C2X2. The Pd/alk-Ti3C2X2 catalyst shows excellent catalytic activity for the hydrodechlorination of 4-chlorophenol and the hydrogenation of 4-nitrophenol in aqueous solution at 25 °C and hydrogen balloon pressure. High initial reaction rates of 216.6 and 126.3 min−1·gpd−1 are observed for the hydrodechlorination of 4-chlorophenol and hydrogenation of 4-nitrophenol, respectively. Most importantly, Pd/alk-Ti3C2X2 exhibits excellent stability and recyclability in both reactions without any promoters. The superior property of Pd/alk-Ti3C2X2 makes it as a potential material for practical applications.

Towards High-Efficiency Hydrogen Production through in situ Formation of Well-Dispersed Rhodium Nanoclusters

Rhodium (Rh)-based materials have been emerged as potential candidates for hydrogen revolution from electrolyzing water or ammonia borane (AB) hydrolysis. Nevertheless, most of the catalysts still suffer from the complex synthetic procedures combined with limited catalytic activity. Additionally, the facile syntheses of Rh catalysts with high efficiencies for both electrochemical water splitting and AB hydrolysis are still challenging. Herein, we develop a simple, green and mass-producible ion-adsorption strategy to produce Rh/C pre-catalyst. The ultrafine and clean Rh nanoclusters immobilized on carbon (in situ-Rh/C) is achieved via the in-situ reduction of the Rh/C pre-catalyst during the hydrogen evolution processes. The in situRh/C catalyst presents an outstanding electrocatalytic performance with low overpotentials of 8 and 30 mV at 10 mA cm current density in 1.0 M KOH and 0.5 M H2SO4, respectively, outperforming the stateof-the-art Pt catalysts. Furthermore, the in situ-Rh/C is also highly active for AB hydrolysis to produce hydrogen with a high turnover frequency of 1246 mol H2 (molRh min) −1 at 25 °C. The in situ formed ultrafine Rh nanoclusters during the hydrogen generation process are responsible for the observed superior catalytic performance. The facile and feasible strategy to realize highly active catalyst shows premise in practical applications.Rh-based materials have emerged as potential candidates for hydrogen revolution from electrolyzing water or ammonia borane (AB) hydrolysis. Nevertheless, most of the catalysts still suffer from the complex synthetic procedures combined with limited catalytic activity. Additionally, the facile syntheses of Rh catalysts with high efficiencies for both electrochemical water splitting and AB hydrolysis are still challenging. Herein, we develop a simple, green, and mass-producible ion-adsorption strategy to produce a Rh/C pre-catalyst (pre-Rh/C). The ultrafine and clean Rh nanoclusters immobilized on carbon are achieved via the inu2005situ reduction of the pre-Rh/C during the hydrogen-evolution process. The resulting inu2005situ Rh/C catalyst presents an outstanding electrocatalytic performance with low overpotentials of 8 and 30u2005mV at 10u2005mAu2009cm-2 in 1.0u2009m KOH and 0.5u2009m H2 SO4 , respectively, outperforming the state-of-the-art Pt catalysts. Furthermore, the inu2005situ Rh/C is also highly active for AB hydrolysis to produce hydrogen with a high turnover frequency of 1246u2005mol H2 u2009molRh-1 u2009min-1 at 25u2009°C. The inu2005situ-formed ultrafine Rh nanoclusters are responsible for the observed superior catalytic performance. This facile inu2005situ strategy to realize a highly active catalyst shows promise for practical applications.