Ni Single Atoms Embedded in Graphene Nanoribbon Sieves for High‐Performance CO₂ Reduction to CO

Abstract

Ni single‐atom catalysts (SACs) are appealing for electrochemical reduction CO2 reduction (CO2RR). However, regulating the balance between the activity and conductivity remains a challenge to Ni SACs due to the limitation of substrates structure. Herein, the intrinsic performance enhancement of Ni SACs anchored on quasi‐one‐dimensional graphene nanoribbons (GNRs) synthesized is demonstrated by longitudinal unzipping carbon nanotubes (CNTs). The abundant functional groups on GNRs can absorb Ni atoms to form rich Ni–N4–C sites during the anchoring process, providing a high intrinsic activity. In addition, the GNRs, which maintain a quasi‐one‐dimensional structure and possess a high conductivity, interconnect with each other and form a conductive porous framework. The catalyst yields a 44 mA cm−2 CO partial current density and 96% faradaic efficiency of CO (FECO) at −1.1 V vs RHE in an H‐cell. By adopting a membrane electrode assembly (MEA) flow cell, a 95% FECO and 2.4 V cell voltage are achieved at 200 mA cm−2 current density. This work provides a rational way to synthesize Ni SACs with a high Ni atom loading, porous morphology, and high conductivity with potential industrial applications.

Efficient Acidic Photoelectrochemical Water Splitting Enabled by Ru Single Atoms Anchored on Hematite Photoanodes

“…This value is significantly lower than the theoretical maximum of 12.5 mA cm –2 . Recently, single-atom catalysts (SACs) have demonstrated impressive performance in various catalytic reactions, such as CO 2 reduction, nitrate electroreduction to ammonia, and methane conversion. − SACs are characterized by the complete exposure of active sites through isolated metal atoms, resulting in a high metal utilization and an increased active surface area. The strong interactions between the fully dispersed metal atoms and the carrier material give SACs a unique electronic structure, enabling optimized reaction interfaces. − To date, single-atom species of Ru and Ir have been predominantly documented on substrates like carbon or metal alloys, with a paucity of studies on their deployment on photoanodes such as hematite. , Integrating single noble-metal atoms onto hematite photoanodes holds great potential for accelerating the OER kinetics while significantly reducing the loading mass of precious metals but presents a significant challenge.…”