Jin-Chao Dong

In Situ Monitoring of Electrooxidation Processes at Gold Single Crystal Surfaces Using Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy

Identifying the intermediate species in an electrocatalytic reaction can provide a great opportunity to understand the reaction mechanism and fabricate a better catalyst. However, the direct observation of intermediate species at a single crystal surface is a daunting challenge for spectroscopic techniques. In this work, electrochemical shell-isolated nanoparticle-enhanced Raman spectroscopy (EC-SHINERS) is utilized to in situ monitor the electrooxidation processes at atomically flat Au(hkl) single crystal electrode surfaces. We systematically explored the effects of crystallographic orientation, pH value, and anion on electrochemical behavior of intermediate (AuOH/AuO) species. The experimental results are well correlated with our periodic density functional theory calculations and corroborate the long-standing speculation based on theoretical calculations in previous electrochemical studies. The presented in situ electrochemical SHINERS technique offers a unique way for a real-time investigation of an electrocatalytic reaction pathway at various well-defined noble metal surfaces.

Pt@h-BN core–shell fuel cell electrocatalysts with electrocatalysis confined under outer shells

Two-dimensional (2D) materials such as graphene and hexagonal boron nitride (h-BN) can be used as robust and flexible encapsulation overlayers, which effectively protect metal cores but allow reactions to occur between inner cores and outer shells. Here, we demonstrate this concept by showing that Pt@h-BN core–shell nanocatalysts present enhanced performances in H2/O2 fuel cells. Electrochemical (EC) tests combined with operando EC-Raman characterizations were performed to monitor the reaction process and its intermediates, which confirm that Pt-catalyzed electrocatalytic processes happen under few-layer h-BN covers. The confinement effect of the h-BN shells prevents Pt nanoparticles from aggregating and helps to alleviate the CO poisoning problem. Accordingly, embedding nanocatalysts within ultrathin 2D material shells can be regarded as an effective route to design high-performance electrocatalysts.

Plasmon‐Enhanced Spectroscopies with Shell‐Isolated Nanoparticles

Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), due to its versatility, has been able to break the long-term limitations of the material- and substrate-specific generalities in the traditional field of surface-enhanced Raman spectroscopy. With a shell-isolated work principle, this method provides an opportunity to investigate successfully in surface, biological systems, energetic materials, and environmental sciences. Both the shell material and core morphology are being improved continuously to meet the requirements in diverse systems, such as the electrochemical studies at single crystal electrode surfaces, in situ monitoring of photoinduced reaction processes, practical applications in energy conversion and storage, inspections in food safety, and the surface-enhanced fluorescence. Predictably, the concept of shell-isolated nanoparticle-enhancement could be expanded to the wider range for the performance of plasmon-enhanced spectral modifications.

Atomic-level insight into super-efficient electrocatalytic oxygen evolution on iron and vanadium co-doped nickel (oxy)hydroxide

It is of great importance to understand the origin of high oxygen-evolving activity of state-of-the-art multimetal oxides/(oxy)hydroxides at atomic level. Herein we report an evident improvement of oxygen evolution reaction activity via incorporating iron and vanadium into nickel hydroxide lattices. X-ray photoelectron/absorption spectroscopies reveal the synergistic interaction between iron/vanadium dopants and nickel in the host matrix, which subtly modulates local coordination environments and electronic structures of the iron/vanadium/nickel cations. Further, in-situ X-ray absorption spectroscopic analyses manifest contraction of metal–oxygen bond lengths in the activated catalyst, with a short vanadium–oxygen bond distance. Density functional theory calculations indicate that the vanadium site of the iron/vanadium co-doped nickel (oxy)hydroxide gives near-optimal binding energies of oxygen evolution reaction intermediates and has lower overpotential compared with nickel and iron sites. These findings suggest that the doped vanadium with distorted geometric and disturbed electronic structures makes crucial contribution to high activity of the trimetallic catalyst.While splitting water could provide a renewable way to produce fuel, highly active catalysts are needed to overcome water oxidation’s sluggish kinetics. Here, authors gain atomic-level insight on metal ion synergetic interactions that boost water oxidation performances in co-doped nickel hydroxide.