The
development of redox-targeting co-catalysts is one of the important
tasks in realizing hybrid photocatalytic systems for CO2 reduction reaction (CO2 RR), which has been sought after
as a promising way to mitigate the energy and environmental crisis.
In this study, hollow nickel hydroxide nanocages are successfully
fabricated via an ion-assisted etching protocol using ZIF-8 as the
structural template, and they are used as cocatalysts along with a
molecular photosensitizer and sacrificial electron donor for reducing
visible-light CO2. A remarkable CO evolution rate of 1.44
× 105 μmol·g ‑1
co‑cat·h–1, a CO selectivity of 96.1%, and a quantum
efficiency of 2.50% are achieved using the optimal cavernous structure
with thin walls, attributing to the significantly improved light harvest
owing to multiple light reflection and scattering, static electron
transfer, abundant surface oxygen vacancies, as well as coherent energy
flow among well-aligned band levels. This study highlights the design
and development of hollow entities toward CO2 RR and provides
insights into the structure-mediated photocatalytic response.
Electrocatalytic conversion of carbon dioxide into high‐value multicarbon (C2+) chemical feedstocks offers a promising avenue to liberate the chemical industry from fossil‐resource dependence and eventually close the anthropogenic carbon cycle but is severely impeded by the lack of high‐performance catalysts. To break the linear scaling relationship of intermediate binding and minimize the kinetic barrier of CO2 reduction reactions, ternary Cu–Au/Ag nanoframes were fabricated to decouple the functions of CO generation and C−C coupling, whereby the former is promoted by the alloyed Ag/Au substrate and the latter is facilitated by the highly strained and positively charged Cu domains. Thus, C2H4 production in an H‐cell and a flow cell occurred with high Faradic efficiencies of 69±5 and 77±2 %, respectively, as well as good electrocatalytic stability and material durability. In situ IR and DFT calculations unveiled two competing pathways for C2H4 generation, of which direct CO dimerization is energetically favored.
The electroreduction of carbon dioxide (CO2RR) to CH4 stands as one of the promising paths for resourceful CO2 utilization in meeting the imminent “carbon‐neutral” goal of the near future. Yet, limited success has been witnessed in the development of high‐efficiency catalysts imparting satisfactory methane selectivity at a commercially viable current density. Herein, a unique category of CO2RR catalysts is fabricated with the yolk–shell nanocell structure, comprising an Ag core and a Cu2O shell that resembles the tandem nanoreactor. By fixing the Ag core and tuning the Cu2O envelope size, the CO flux arriving at the oxide‐derived Cu shell can be regulated, which further modulates the *CO coverage and *H adsorption at the Cu surface, consequently steering the CO2RR pathway. Density functional theory simulations show that lower CO coverage favors methane formation via stabilizing the intermediate *CHO. As a result, the best catalyst in the flow cell shows a high CH4 Faraday efficiency of 74 ± 2% and partial current density of 178 ± 5 mA cm−2 at −1.2 VRHE, ranking above the state‐of‐the‐art catalysts reported today for methane production. These findings mark the significance of precision synthesis in tailoring the catalyst geometry for achieving desired CO2RR performance.
Electrochemical CO2 reduction (CO2RR) in a product-orientated and energy-efficient manner relies on rational catalyst design guided by mechanistic understandings. In this study, the effect of conducting support on the CO2RR behaviors of semi-conductive metal-organic framework (MOF) — Cu3(HITP)2 are carefully investigated. Compared to the stand-alone MOF, adding Ketjen Black greatly promotes C2H4 production with a stabilized Faradaic efficiency between 60-70% in a wide potential range and prolonged period. Multicrystalline Cu nano-crystallites in the reconstructed MOF are induced and stabilized by the conducting support via current shock and charge delocalization, which is analogous to the mechanism of dendrite prevention through conductive scaffolds in metal ion batteries. Density functional theory calculations elucidate that the contained multi-facets and rich grain boundaries promote C–C coupling while suppressing HER. This study underlines the key role of substrate-catalyst interaction, and the regulation of Cu crystalline states via conditioning the charge transport, in steering the CO2RR pathway.
The
deployment of Li metal batteries has been significantly tethered
by uncontrollable lithium dendrite growth, especially in heavy-duty
operations. Herein, we implement an in situ surface
transformation tactic exploiting the vapor-phase solid–gas
reaction to construct an artificial solid-electrolyte interphase (SEI)
of Li2Se on Li metal anodes. The conformal Li2Se layer with high ionic diffusivity but poor electron conductivity
effectively restrains the Li/Li+ redox conversion to the
Li/Li2Se interface, and further renders a smooth and chunky
Li deposition through homogenized Li+ flux and promoted
redox kinetics. Consequently, the as-fabricated Li@Li2Se
electrodes demonstrate superb cycling stability in symmetric cells
at both high capacity and current density. The merits of inhibited
dendrite growth and side reactions on the stabilized Li@Li2Se anode are further manifested in Li–O2 batteries,
greatly extending the cycling stability and energy efficiency.
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