Regulating the Synergistic Effect in Bimetallic Two-Dimensional Polymer Oxygen Evolution Reaction Catalysts by Adjusting the Coupling Strength Between Metal Centers.

Bimetallic electrocatalysts with its superior performance has a broad application prospect in oxygen evolution reaction (OER), but the fundamental understanding of the mechanism of synergistic effect is still limited since there lacks a practical way to decouple the influence factors on the intrinsic activity of active sites from others. Herein, a series of bimetallic Co-Ni two-dimensional polymer (2DP) model OER catalysts with well-defined architecture, monolayer characteristic, were designed and synthesized to explore the influence of the coupling strength between metal centers on OER performance. The coupling strength was regulated by adjusting the spacing between metal centers or the conjugation degree of bridge skeleton. Among the examined 2DPs, CoTAPP-Ni-MF-2DP, which has the strongest coupling strength between metal centers exhibited the best OER performance. These model systems can help to explore the precise structure-performance relationships, which is important for the rational catalyst design at the atomic/molecular levels.

Spatial Well-defined Bimetallic Two-Dimensional Polymers with Single-Layer Thickness for Electrocatalytic Oxygen Evolution Reaction.

Innovative bimetallic materials provide more possibilities for further improving the performance of oxygen evolution reaction (OER) electrocatalysts. However, it is still a great challenge to rationally design bimetallic catalysts because there is not a practical way to decouple the factors influencing the intrinsic activity of active sites from others, thus hindering in-depth understanding of the mechanism. Herein, we provide a rational design of bimetallic Ni, Co two-dimensional polymer model OER catalyst. The well-defined architecture, identical density of active sites and monolayer characteristic allow us to decouple the intrinsic activity of active sites from other factors. The results confirmed that the relative position and local coordination environment has significant effect on the synergistic effect of the bimetallic centres. The highest electrocatalytic activity with the turnover frequency value up to 26.19 s-1 was achieved at the overpotential of 500 mV.

WO3@Bi2WO6/NiWO4 Nanocomposites with Outstanding Visible-Light-Driven Photocatalysis for the Degradation of Organic Dyes.

By hydrothermal reaction, the WO3@Bi2WO6/NiWO4 nanocomposite was prepared by the coprecipitation reaction between Bi3+/Ni2+ and WO2-4 in the presence of urea and PVP. It resulted in the formation of uniform and well-dispersed nanocomposite structures with ultrathin Bi2WO6/NiWO4 nanosheets attached with ultrafine WO3 nanoparticles. The nanocomposites exhibited a wide light absorbance up to 680 nm with low indirect band gaps of 2.54 eV, leading to outstanding photocatalytic efficiency for the degradation of both Rhodamine B (Rh B) and Xylenol Orange (XO) under visible light. With irradiation for only 15 minutes, Rh B was nearly completely degraded. XO, which is difficult to degrade usually, and the strong absorption peak nearly vanishes in about 60 min. The ultrathin Bi2WO6/NiWO4 nanosheets and ultrafine WO3 nanoparticles mean high specific areas and high active sites. A lot of hydroxy groups in WO3@Bi2WO6/NiWO4-III due to the presence of Ni and Bi helps for the formation of ˙OH. According to the ladder theory, the photogenerated e- and h+ by the irradiation light of high wavelength according with band gap can be activated again by that of lower wavelength step by step. The lower wavelength means the higher energy. The broader adsorption means the higher efficiency for energy adsorption and more e- and h+ with higher energy were activated to photocatalytically degrade dyes. This provides new potential to explore nanocomposites for efficient photo-driven degradation of organic dyes under visible light irradiation.