Bimetallic metal–organic frameworks and MOF-derived composites: Recent progress on electro- and photoelectrocatalytic applications

Oxygen evolution reaction (OER), as a relevant half reaction for water splitting to address the energy crisis, has captured a great deal of attention. However, this technology has always been impeded by the lack of a highly efficient and stable electrocatalyst. Amorphous materials, which possess long‐range disorder and only short‐range order over a few atoms, are often superior to their crystalline counterparts in electrocatalysis owing to their more active sites, broader chemical composition range, and more structural flexibility. This review first introduces some assessment criteria for the OER and then presents theoretical modeling of the OER mechanisms and the state‐of‐the‐art amorphous transition metal‐based OER electrocatalysts, involving oxides, hydroxides, sulfides, phosphides, borides, and their composites, as well as their practical applications in the OER. Finally, recent development, existing challenges, and future perspectives for amorphous transition metal‐based OER electrocatalysts are discussed. This paper offers valuable guidance in designing highly efficient and stable amorphous OER electrocatalysts for future energy applications.

Recent Development and Future Perspectives of Amorphous Transition Metal‐Based Electrocatalysts for Oxygen Evolution Reaction

It is highly desirable to cut down the electron transfer resistance, improve both site activity and site populations of layered double hydroxides (LDHs) for enhanced electrochemical activity of oxygen evolution reaction (OER). Herein, the hybrid that Co-LDH nanosheets shells grown on Ag nanowires (NWs) cores (Ag@Co-LDH) was constructed and applied as a favorable OER electrocatalyst. The high conductivity of Ag NWs and heterointerface between Ag NWs and Co-LDH gravely accelerate electron transfer. Co-LDH with ultrathin sheet-like structure and abundant grain boundary defects effectively provide lots of active sites. The optimized local environment of Co atoms by Ag dopants and plentiful amorphous regions strongly enhance the intrinsic activity of active site. Therefore, the as-prepared Ag@Co-LDH demonstrates distinguished OER activity with a low overpotential of 217 mV at the current density of 10 mA cm−2, which is superior to most reported advanced OER electrocatalysts and even commercial Ir/C. Moreover, benefiting from the unique structure and stable heterointerface, Ag@Co-LDH also exhibits robust cycling stability and long-term durability proved by accelerated degradation test (ADT) and galvanostatic test, respectively. This finding provides a practical design direction for high-performance LDH-based OER electrocatalysts.

Hierarchically constructed Ag nanowires shelled with ultrathin Co-LDH nanosheets for advanced oxygen evolution reaction

Electrochemical water splitting is a mature technology for hydrogen generation. Numerous studies have focused on the development of highly efficiency electrocatalysts to produce hydrogen and oxygen from water electrolysis through...

First-row transition metal-based materials derived from bimetallic metal-organic frameworks as highly efficient electrocatalysts for electrochemical water splitting

Given the carbon limitation of low C/N wastewater, the improvement of nitrogen-removal efficiency remains a challenging task of municipal wastewater treatment plants (WWTPs) in China. In this study, a partial nitrification/anammox (PN/A) system was established to facilitate the anaerobic-anoxic-aerobic (A2/O) treatment of low C/N (C/N = 3) wastewater with insufficient carbon sources. Effects of dissolved oxygen (DO) concentration and internal reflux ratio on nitrogen-removal efficiency and pathway were investigated. Under the optimal DO (0.5–0.8 mg·L−1) and internal reflux ratio (250%), the highly efficient NH4+-N removal (97.21%) and TN removal (80.92%) were achieved based on PN/A. Moreover, the relative abundance of ammonia-oxidizing bacteria (Nitrosomonas) was 3 times higher than the abundance of nitrite-oxidizing bacteria (Nitrospira) in phase V, which was the main cause of PN in the reactor. Anaerobic ammonia-oxidizing bacteria (Candidatus Brocadia, Pirellula, and Gemmata) were also found and considered as the key microbes involved in anammox. This study reports that the A2/O process can achieve advanced nitrogen removal of low C/N wastewater based on PN/A by optimizing conventional process parameters. The outcomes of this study may provide practical engineering applications as a reference for nitrogen removal based on the A2/O process.

https://www.mdpi.com/2073-4441/15/12/2300/pdf?version=1687258423

Analysis of the Partial Nitrification/Anammox Performance and Microbial Structure of Low C/N Wastewater by A2/O Process

HFOs are currently being adopted for adsorption refrigeration applications due to their zero ozone depletion potential and paltry global warming potential. In this study, a constant volume variable pressure (CVVP) system is designed and built to experimentally investigate the adsorption characteristics of HFO-1234ze(E) onto Maxsorb III. Experiments were performed to obtain refrigerant uptakes at adsorption temperatures of 30, 40, and 50°C at variable refrigerant pressures. The maximum experimental adsorption uptake is 1.73 kg•kg–1 at 0.607 relative pressure. The uptake starts to increase sharply from 0.01 relative pressure and slows down at 0.2 relative pressure. The experimental adsorption isotherm data were correlated with Tóth and Dubinin-Astakhov (D–A) adsorption isotherm models. Uptake difference based on Tóth and D–A adsorption model at possible working temperature has been simulated. Isosteric heats of adsorption were determined from Clausius–Clapeyron relation, and their dependence on uptake was also analyzed and reported. Additionally, the specific cooling effects and coefficient of performance are investigated. These findings are crucial for the system performance assessment of a practical adsorption refrigeration system. 

Study on the adsorption characteristics of Maxsorb Ⅲ/HFO-1234ze(E) pair for adsorption refrigeration applications

A Flower Composite Catalyst in Situ Grown on Conductive Iron Foam： Revealing the Enhancement of Oer Activity by Cooperat Ing of Amorphous Ni Nanosheets With  Spinel Nife2o4

Lei Ye

Papers

Analysis of the Partial Nitrification/Anammox Performance and Microbial Structure of Low C/N Wastewater by A2/O Process

Study on the adsorption characteristics of Maxsorb Ⅲ/HFO-1234ze(E) pair for adsorption refrigeration applications

A Flower Composite Catalyst in Situ Grown on Conductive Iron Foam： Revealing the Enhancement of Oer Activity by Cooperat Ing of Amorphous Ni Nanosheets With Spinel Nife2o4