In Silico Design of Covalent Organic Framework-Based Electrocatalysts

Abstract

Covalent organic frameworks (COFs) are an emerging type of porous crystalline material for efficient catalysis of the oxygen evolution reaction (OER). However, it remains a grand challenge to address the best candidates from thousands of possible COFs. Here, we report a methodology for the design of the best candidate screened from 100 virtual M–N x O y (M = 3d transition metal)-based model catalysts via density functional theory (DFT) and machine learning (ML). The intrinsic descriptors of OER activity of M–N x O y were addressed by the machine learning and used for predicting the best structure with OER performances. One of the predicted structures with a Ni–N 2 O 2 unit is subsequently employed to synthesize the corresponding Ni–COF. X-ray absorption spectra characterizations, including XANES and EXAFS, validate the successful synthesis of the Ni–N 2 O 2 coordination environment. The studies of electrocatalytic activities confirm that Ni–COF is comparable with the best reported COF-based OER catalysts. The current density reaches 10 mA cm –2 at a low overpotential of 335 mV. Furthermore, Ni–COF is stable for over 65 h during electrochemical testing. This work provides an accelerating strategy for the design of new porous crystalline-material-based electrocatalysts.

Metalated covalent organic frameworks: from synthetic strategies to diverse applications

“…Recently, Deng et al used machine learning to predict the performances of metalated 3D salen-COFs in OER and identified Ni-salen-COFs to be the best candidate. 532 The synthetic experiments well verified the predicted results, and the Nisalen-COF was overall better than the corresponding Co-, Fe-, Cu-, and Zn-based analogs in Tafel slope, charge transfer resistance, and electrochemical double-layer capacitance. This theoretical and experimental study not only develops the synthesis method of metalated COF electrocatalysts, but also provides insights for material design.…”

“…Theoretical calculations are powerful tools for studying the structure and properties of materials; for example, first-principles calculations, molecular dynamics simulations, and grand canonical Monte Carlo simulations have been applied in the study of the binding sites of light metals in COFs, 402 optimization of the unit cell structure of COFs, 852 prediction of gas adsorption behaviors, 412,873,874 and design and screening of electrocatalysts. 532,875,876 However, due to computational bottlenecks, theoretical simulations are usually performed on fragments of COFs, leading to one-sided conclusions. Moreover, even such degraded theoretical calculations are rarely used to optimize the metalation synthesis conditions, catalyst screening, prediction of electronic properties, and material-biointerface interaction studies, although they are logically feasible and very important.…”

Modulating the Band Structure of Metal Coordinated Salen COFs and an In Situ Constructed Charge Transfer Heterostructure for Electrocatalysis Hydrogen Evolution

“…Also, Salen complexes as active centers are capable of regulating the coordination environment and local structure flexibly with the help of metal ion exchange. [ 33 , 40 ] Therefore, these unique characteristics enable Metal‐Salen COF EDA as a model to be researched structure–activity relationship in electrocatalysis (see Section 3 for an explanation). However, the electrocatalytic performance of Metal‐Salen COF EDA may be limited by conductivity.…”

Digital Innovation Enabled Nanomaterial Manufacturing; Machine Learning Strategies and Green Perspectives

“…A high correlation was shown to govern the relationship of electrostatic interaction and adsorption energy of intermediates. Final screening of material features showed that four intrinsic factors are only required to describe the OER activity of the model catalysts metal-N x O y , while the predictions could be well-correlated with DFT predictions [ 111 ].…”