The critical bottleneck of electrocatalytic CO 2 reduction reaction (CO 2 RR) lies in its low efficiency at high overpotential caused by competitive hydrogen evolution. It is challenging to develop an efficient catalyst achieving both high current density and high Faradaic efficiency (FE) for CO 2 RR. Herein, we synthesized fluorine-doped cagelike porous carbon (F-CPC) by purposely tailoring its structural properties. The optimized F-CPC possesses large surface area with moderate mesopore and abundant micropores as well as high electrical conductivity. When used as catalyst for CO 2 RR, F-CPC exhibits FE of 88.3% for CO at −1.0 V vs RHE with a current density of 37.5 mA•cm −2 . Experimental results and finite element simulations demonstrate that the excellent CO 2 RR performance of F-CPC at high overpotential should be attributed to its structure-enhanced electrocatalytic process stemming from its cagelike morphology.

Copper oxide-based materials effectively electrocatalyze carbon dioxide reduction (CO 2 RR). To comprehend their role and achieve high CO 2 RR activity, Cu + in copper oxides must be stabilized. As an electrocatalyst, Cu 2 O nanoparticles were decorated with hexagonal boron nitride (h-BN) nanosheets to stabilize Cu + . The C 2 H 4 /CO ratio increased 1.62-fold in the CO 2 RR with Cu 2 OÀ BN compared to that with Cu 2 O. Experimental and theoretical studies confirmed strong electronic interactions between the two components in Cu 2 OÀ BN, which strengthens the CuÀ O bonds. Electrophilic h-BN receives partial electron density from Cu 2 O, protecting the CuÀ O bonds from electron attack during the CO 2 RR and stabilizing the Cu + species during longterm electrolysis. The well-retained Cu + species enhanced the C 2 product selectivity and improved the stability of Cu 2 OÀ BN. This work offers new insight into the metal-valence-state-dependent selectivity of catalysts, enabling the design of advanced catalysts.

Carbon electrodes are of great importance in constructing high-performance capacitive deionization (CDI) devices. However, the use of conventional carbon electrodes for CDI is limited because of their poor mechanical stability and low mass loading. Herein, we report a binder-free, freestanding, robust, and ultrathick carbon electrode derived from a wood carbon framework (WCF) for CDI applications. The WCF inherits the unique structure of natural basswood, containing straightly aligned channels interconnected with highly ordered, open, and hierarchical pores. A CDI device based on thick WCF electrodes (1200 μm, equal to a mass loading of 50 mg cm) exhibits a remarkable areal salt adsorption capacity (SAC) of 0.3 mg cm, a high volumetric SAC of 2.4 mg cm, and a competitive gravimetric SAC of 5.7 mg g. Also, the good mechanical strength and water tolerance of the WCF electrodes improve the cycling stability of the CDI device. Finite element simulations of ion transport behavior indicate that the unique structure of the WCF substantially facilitates ion transport within the ultrathick CDI electrodes. This work provides a viable route to the rational design of freestanding and ultrathick electrodes for CDI applications and offers insights into the structure-performance relationship of CDI electrodes.

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The carbon-based electrodes have experienced great progress for capacitive desalination owning to the high conductivity and low cost. However, the fundamental issue of the origin of capacitive activity is far...