Ir single atoms on NiFeZn-LDH matrix for exceptional oxygen evolution reaction

To address the sluggish kinetics of the oxygen evolution reaction(OER),a potential approach is to rationally design and fabricate extremely effective single atom catalysts(SACs).Using an appropriate matrix to stabilize single-atom active centers with optimal geometric and electronic structures is crucial for enhancing catalytic activity.Herein,we report the design and fabrication of Ir single atoms on NiFeZn layered double hydroxide(Ir-SAC/NiFeZn-LDH)electrocatalyst for highly efficient and stable OER.It is investigated that the NiFeZn support exhibits abundant defect sites and unsaturated coordination sites.These sites function to anchor and stabilize single Ir single atoms on the support.The strong synergetic electronic interaction between the Ir single atoms and the NiFeZn matrix resulted in remarkable OER performance of the as-fabricated Ir-SAC/NiFeZn catalyst.With a loading Ir content of 1.09 wt.%,this catalyst demonstrates a highly stable OER activity,with an overpotential of 196 mV at 10 mA·cm^(−2) and a small Tafel slope of 35 mV·dec^(−1) for the OER in a 1 M KOH solution.These results significantly surpass the performance of the commercially available IrO_(2) catalyst.

Selective hydrogenation of N-heterocyclic compounds over rhodium-copper bimetallic nanocrystals under ambient conditions

Bimetallic nanocrystals (BMNCs) with distinguished electronic and chemical properties from those of their parent metals,offer the opportunity to obtain new catalysts with enhanced selectivity,activity,and stability.Here we describe the facile synthesis of rhodium-copper bimetallic system with different compositions and uniform morphology for chemo selective hydrogenation of functionalized quinolines.Our findings demonstrate that Rh-Cu BMNCs exhibited composition dependent activity and selectivity.BMNCs with rhodium to copper ratio 3:1 surpassed individual Rh and Cu and other compositions both in activity and selectivity for quinolines hydrogenation and performed even better than Rh/C with same amount of Rh.Rh3Cui catalyst displayed excellent tolerance for synthetically significant functional groups such as -OH,NH2,F,particularly for aldehyde group which is very reactive towards reduction.These results suggested that the coexistence of rhodium and copper metals play important role in the enhancement of catalytic activity due to synergistic effects and revealed that bimetallic nanocrystals can be promising as practical catalysts for selective hydrogenation of quinoline and other substrates.