Increasing concerns about the atmospheric CO2 concentration and its impact on the environment are motivating researchers to discover new materials and technologies for efficient CO2 capture and conversion. Here, we report a study of the adsorption of CO2, CH4, and H2 on boron nitride (BN) nanosheets and nanotubes (NTs) with different charge states. The results show that the process of CO2 capture/release can be simply controlled by switching on/off the charges carried by BN nanomaterials. CO2 molecules form weak interactions with uncharged BN nanomaterials and are weakly adsorbed. When extra electrons are introduced to these nanomaterials (i.e., when they are negatively charged), CO2 molecules become tightly bound and strongly adsorbed. Once the electrons are removed, CO2 molecules spontaneously desorb from BN absorbents. In addition, these negatively charged BN nanosorbents show high selectivity for separating CO2 from its mixtures with CH4 and/or H2. Our study demonstrates that BN nanomaterials are excellent absorbents for controllable, highly selective, and reversible capture and release of CO2. In addition, the charge density applied in this study is of the order of 1013 cm–2 of BN nanomaterials and can be easily realized experimentally.

Charge-controlled switchable CO2 capture on boron nitride nanomaterials

Single-metal site catalysts have exhibited highly efficient electrocatalytic properties due to their unique coordination environments and adjustable local structures for reactant adsorption and electron transfer. They have been widely studied for many electrochemical reactions, including oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, it remains a significant challenge to realize high-efficiency bifunctional catalysis (ORR/OER) with single-metal-type active sites. Herein, we report atomically dispersed Fe–Co dual metal sites (FeCo–NC) derived from Fe and Co co-doped zeolitic imidazolate frameworks (ZIF-8s), aiming to build up multiple active sites for bifunctional ORR/OER catalysts. The atomically dispersed FeCo–NC catalyst shows excellent bifunctional catalytic activity in alkaline media for the ORR (E1/2 = 0.877 V) and the OER (Ej=10 = 1.579 V). Moreover, its outstanding stability during the ORR and the OER is comparable to noble-metal catalysts (Pt/C and RuO2). The atomic dispersion state, coordination structure, and the charge density difference of the dual metal site FeCo–NC were characterized and determined using advanced physical characterization and density functional theory (DFT) calculations. The FeCo–N6 moieties are likely the main active sites simultaneously for the ORR and the OER with improved performance relative to the traditional single Fe and Co site catalysts. We further incorporated the FeCo–NC catalyst into an air electrode for fabricating rechargeable and flexible Zn–air batteries, generating a superior power density (372 mW cm–2) and long-cycle (over 190 h) stability. This work would provide a method to design and synthesize atomically dispersed multi-metal site catalysts for advanced electrocatalysis. 

Atomically Dispersed Fe–Co Dual Metal Sites as Bifunctional Oxygen Electrocatalysts for Rechargeable and Flexible Zn–Air Batteries

Achieving efficient and durable nonprecious hydrogen evolution reaction (HER) catalysts for scaling up alkaline water/seawater electrolysis is desirable but remains a significant challenge. Here, a heterogeneous Ni‐MoN catalyst consisting of Ni and MoN nanoparticles on amorphous MoN nanorods that can sustain large‐current‐density HER with outstanding performance is demonstrated. The hierarchical nanorod–nanoparticle structure, along with a large surface area and multidimensional boundaries/defects endows the catalyst with abundant active sites. The hydrophilic surface helps to achieve accelerated gas‐release capabilities and is effective in preventing catalyst degradation during water electrolysis. Theoretical calculations further prove that the combination of Ni and MoN effectively modulates the electron redistribution at their interface and promotes the sluggish water‐dissociation kinetics at the Mo sites. Consequently, this Ni‐MoN catalyst requires low overpotentials of 61 and 136 mV to drive current densities of 100 and 1000 mA cm−2, respectively, in 1 m KOH and remains stable during operation for 200 h at a constant current density of 100 or 500 mA cm−2. This good HER catalyst also works well in alkaline seawater electrolyte and shows outstanding performance toward overall seawater electrolysis with ultralow cell voltages.

Efficient Alkaline Water/Seawater Hydrogen Evolution by a Nanorod‐Nanoparticle‐Structured Ni‐MoN Catalyst with Fast Water‐Dissociation Kinetics

Gas sensing materials have been widely explored recently owing to their versatile environmental and agriculture monitoring applications The present study advocates the electronic response of Zn-decorated inorganic B12P12 nanoclusters to CO2 gas Herein, a series of systems CO2-Zn-B12P12 (E1-E4) are designed by adsorption of CO2 on Zn-decorated B12P12 nanoclusters, and their electronic properties are explored by density functional theory Initially, placement of Zn on B12P12 delivers four geometries named as D1-D4, with adsorption energy values of -5712, -2294, -2103, and -1407 kJ/mol, respectively, and CO2 adsorption on a pure B12P12 nanocage delivers one geometry with an adsorption energy of -488 kJ/mol However, the interaction of CO2 with D1-D4 systems confers four geometries named as E1 (Ead = -7512 kJ/mol), E2 (Ead = -2589 kJ/mol), E3 (Ead = -4243 kJ/mol), and E4 (Ead = -2873 kJ/mol) Various electronic parameters such as dipole moment, molecular electrostatic potential analysis, frontier molecular orbital analysis, QNBO, global descriptor of reactivity, and density of states are also estimated in order to understand the unique interaction mechanism The results of these analyses suggested that Zn decoration on B12P12 significantly favors CO2 gas adsorption, and a maximum charge separation is also noted when CO2 is adsorbed on the Zn-B12P12 nanocages Therefore, the Zn-decorated B12P12 nanocages are considered as potential candidates for application in CO2 sensors

Designing Novel Zn-Decorated Inorganic B12P12 Nanoclusters with Promising Electronic Properties: A Step Forward toward Efficient CO2 Sensing Materials.

The development of a high-performance electrocatalyst for oxygen evolution reaction (OER) is imperative but challenging. Here, a partial sulfidation route to construct Ni2Fe-LDH/FeNi2S4 heterostructure on nickel foam (Ni2Fe-LDH/FeNi2S4/NF) by adjusting the hydrothermal duration is reported. The heterostructures afford abundant hydroxide/sulfide interfaces that offer plentiful active sites, rapid charge and mass transfer, favorable adsorption energy to oxygenated species (OH− and OOH) evidenced by the density functional theory calculations, which synergistically boost the alkaline water oxidation. In the 1.0 m KOH solution, Ni2Fe-LDH/FeNi2S4/NF exhibits an excellent OER catalytic activity with a much smaller overpotential (240 mV) to reach the current density of 100 mA cm−2 than single-phase Ni2Fe-LDH/NF (279 mV) or FeNi2S4/NF (271 mV). More impressively, 2000 cycles of cyclic voltammetry scan for water oxidation results in the formation of a sulfate layer over the catalyst. The corresponding post-catalyst demonstrates better OER activity and durability than the initial one in the alkaline simulated seawater electrolyte. The post-Ni2Fe-LDH/FeNi2S4/NF delivers smaller overpotential (250 mV) at 100 mA cm−2 and longer stability time than the original form (260 mV). The post-formed sulfate passivating layer is responsible for the outstanding corrosion resistance of the salty-water oxidation anode since it can effectively repel chloride. 

Partial Sulfidation Strategy to NiFe‐LDH@FeNi <sub>2</sub> S <sub>4</sub> Heterostructure Enable High‐Performance Water/Seawater Oxidation

Chemical Vapor Deposition for N/S-Doped Single Fe Site Catalysts for the Oxygen Reduction in Direct Methanol Fuel Cells

Highly Selective Electrocatalytic CO2 Reduction to Methanol on Iridium Dioxide with CO* Spectators

Density functional theory (DFT) calculations have been carried out to study the capacity of the B12N12 nanocage encapsulated with alkali metals (Li, Na, K) for the CO2 adsorption and activation. It...

CO2 Adsorption on the B12N12 Nanocage Encapsulated with Alkali Metals: A Density Functional Study

Theoretical study on the two novel planar-type all-nitrogen N44− anions: Structures, stability, reaction rate and their stable mechanisms via protonation

Pd/CeO2 catalysts show superior catalytic performance owing to their optimal cycling activity and stability. In this study, single-atom Pd and eight-atom Pd nanoparticle clusters were supported on the surface of CeO2(110) to investigate the effect of loaded-metal size on the catalytic performance of the Pd–CeO2 system for CO2 reduction. We investigated the CO2 reduction reaction (CRR) that produces C1 products (CO, HCOOH, CH3OH, and CH4) on Pd8/CeO2 and Pd/CeO2 by density functional theory. The structures, CO2 adsorption configurations, and CO2 reduction mechanisms of these two electrocatalysts were systematically studied. Subsequently, different reduction pathways on Pd8/CeO2 and Pd/CeO2 were investigated to identify the optimal reaction pathway for further assessment. The results showed that both of these catalysts are more selective towards the production of CH3OH than CH4. Moreover, compared to Pd/CeO2 and Pd4/CeO2 (from a previously reported study) the production of CH3OH via the CRR on Pd8/CeO2 exhibited the lowest limiting potential. These results demonstrate the superiority of Pd8/CeO2 as an electrocatalyst for the electrochemical reduction of CO2 to CH3OH.

He Zhao

Papers

Chemical Vapor Deposition for N/S-Doped Single Fe Site Catalysts for the Oxygen Reduction in Direct Methanol Fuel Cells

Highly Selective Electrocatalytic CO2 Reduction to Methanol on Iridium Dioxide with CO* Spectators

CO2 Adsorption on the B12N12 Nanocage Encapsulated with Alkali Metals: A Density Functional Study

Theoretical study on the two novel planar-type all-nitrogen N44− anions: Structures, stability, reaction rate and their stable mechanisms via protonation

A theoretical study of the electrochemical reduction of CO2 on cerium dioxide supported palladium single atoms and nanoparticles.