Hot Carrier Lifetimes and Electrochemical Water Dissociation Enhanced by Nickel Doping of a Plasmonic Electrocatalyst

Integration of Co Single Atoms and Ni Clusters on Defect-Rich ZrO2 for Strong Photothermal Coupling Boosts Photocatalytic CO2 Reduction

We report a solvothermal method for the synthesis of an oxygen vacancy-enriched ZrO2 photocatalyst with Co single atoms and Ni clusters immobilized on the surface. This catalyst presents superior performance for the reduction of CO2 in H2O vapor, with a CO yield reaching 663.84 μmol g-1 h-1 and a selectivity of 99.52%. The total solar-to-chemical energy conversion efficiency is up to 0.372‰, which is among the highest reported values. The success, on one hand, depends on the Co single atoms and Ni clusters for both extended spectrum absorption and serving as dual-active centers for CO2 reduction and H2O dissociation, respectively; on the other hand, this is attributed to the enhanced photoelectric and thermal effect induced by concentrated solar irradiation. We demonstrate that an intermediate impurity state is formed by the hybridization of the d-orbital of single-atom Co with the molecular orbital of H2O, enabling visible-light-driven excitation over the catalyst. In addition, Ni clusters play a crucial role in altering the adsorption configuration of CO2, with the localized surface plasmon resonance effect enhancing the activation and dissociation of CO2 induced by visible-near-infrared light. This study provides valuable insights into the synergistic effect of the dual cocatalyst toward both efficient photothermal coupling and surface redox reactions for solar CO2 reduction.

Uncovering Photoelectronic and Photothermal Effects in Plasmon-Mediated Electrocatalytic CO2 Reduction

Plasmon-mediated electrocatalysis that rests on the ability of coupling localized surface plasmon resonance (LSPR) and electrochemical activation, emerges as an intriguing and booming area. However, its development seriously suffers from the entanglement between the photoelectronic and photothermal effects induced by the decay of plasmons, especially under the influence of applied potential. Herein, using LSPR-mediated CO2 reduction on Ag electrocatalyst as a model system, we quantitatively uncover the dominant photoelectronic effect on CO2 reduction reaction over a wide potential window, in contrast to the leading photothermal effect on H2 evolution reaction at relatively negative potentials. The excitation of LSPR selectively enhances the CO faradaic efficiency (17-fold at -0.6 VRHE ) and partial current density (100-fold at -0.6 VRHE ), suppressing the undesired H2 faradaic efficiency. Furthermore, in situ attenuated total reflection-surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) reveals a plasmon-promoted formation of the bridge-bonded CO on Ag surface via a carbonyl-containing C1 intermediate. The present work demonstrates a deep mechanistic understanding of selective regulation of interfacial reactions by coupling plasmons and electrochemistry.

Probing local charge transfer processes of Pt-Au heterodimers in plasmon-enhanced electrochemistry by CO stripping techniques

CO-stripping experiments are employed as a highly structure-sensitive and in situ strategy to explore the mechanisms of plasmon-enhanced electrooxidation reactions. By using Pt-Au heterodimers as a model catalyst, the plasmon-induced current and potential changes on Pt and Au sites can be identified and explained.

Hot or Not? Reassessing Mechanisms of Photocurrent Generation in Plasmon-Enhanced Electrocatalysis

It is now widely accepted that certain effects arising from localised surface plasmon resonance, such as enhanced electromagnetic fields, hot carriers, and thermal effects, can facilitate electrocatalytic processes. This newly emerging field of research is commonly referred to as plasmon-enhanced electrocatalysis (PEEC) and is attracting increasing interest from the research community, particularly regarding harnessing the high energy of hot carriers. However, this has led to a lack of critical analysis in the literature, where the participation of hot carriers is routinely claimed due to their perceived desirability, while the contribution of other effects is often not sufficiently investigated. As a result, correctly differentiating between the possible mechanisms at play has become a key point of contention. In this review, we specifically focus on the mechanisms behind photocurrents observed in PEEC and critically evaluate the possibility of alternative sources of current enhancement in the reported PEEC systems. Furthermore, we present guidelines for the best experimental practices and methods to distinguish between the various enhancement mechanisms in PEEC.