Multicomponent 3d-Metal Nanoparticles in Amorphous Carbon Sponge for Electrocatalysis Water Splitting

Abstract

Design and understanding of complex material systems represent an intriguing pursuit for chemical research and could lead to functional materials with superior performance and new applications. Here, a highly porous amorphous carbon sponge incorporating uniformly dispersed multicomponent 3d-metal nanoparticles was prepared from heterometal cluster-based metal−organic frameworks (MOFs) of [M 3 (bpt) 2 (DMF) 2 (H 2 O) 2 ] (M = Fe 2+ , Co 2+ , and Ni 2 ) through controllable structural transformation under mild temperature. The octahedral coordination geometry of metal ions in the [M 3 (COO) 6 ] nodes is highly versatile and compatible with various metal ions, thus rendering the metal mode as an ideal platform to assemble mono-, bi-, and trimetallic clusters as precursors for heterometallic nanoparticles. A mild temperature of 400 °C was found to be optimal to produce NiCoFeO x @C-400, featuring extremely small particles as low as 5 nm in diameter, high-content amorphous carbon, and coexistence of different metal oxide phases covering M 3 O 4 , M 2 O 3 , and MO besides the metal alloy nanoparticles. In contrast, higher annealing temperatures of 600 and 800 °C lead to aggregated particles above 100 nm, low-content and dense graphitized carbon, and simple oxide phases. The presence of heterometals, multicomponent synergism, rich heterojunctions, phase boundaries, and porous carbon promotes mass transport and contributes to the prominent electrocatalyst performance of NiCoFeO x @C-400, which is better than that of bi/ monometallic species and high-temperature derivatives. When coated on nickel foam, NiCoFeO x @C-400 realizes small overpotentials of 253 and 84 mV for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively, and can work with a cell voltage of merely 1.63 V for durable overall water splitting, under a current density of 10 mA cm −2 using 1 M KOH as the electrolyte. This study presents an efficient strategy to prepare and expand chemically complex systems for energy conversion application.

Synergistic Interplay of Dual‐Active‐Sites on Metallic Ni‐MOFs Loaded with Pt for Thermal‐Photocatalytic Conversion of Atmospheric CO2 under Infrared Light Irradiation

“…Ni‐MOF was synthesized via a one‐step solvothermal reaction in a mixture of water and N,N‐dimethylformamide (DMF) solvent [25] . According to the results of single‐crystal X‐ray diffraction studies, [25,26] Ni‐MOF crystallizes in the trigonal crystal system of the R $${\mathrel{\mathop{{\rm { 3}}}\limits^{{\rm -}}}\ }$$ space group and exhibits a three‐dimensional (3D) network based on [Ni 3 (COO) 6 ] clusters with hexagonal 1D channels of 1.3 nm diameter (Figure 1a). Pt‐loaded Ni‐MOFs were also prepared by the same method as that used for Ni‐MOF by adding different amounts of the H 2 PtCl 6 precursor in the solution before solvothermal treatment.…”

“…Figure 1b shows the powder X‐ray diffraction (PXRD) patterns of the x %‐Pt/Ni‐MOF samples, indicating that the structure of Ni‐MOF did not change after Pt loading. According to the single‐crystal X‐ray diffraction analysis, during the solvothermal reaction, the DMF and H 2 O molecules coordinate with the Ni sites of Ni‐MOF [25,26] . For generating open metal sites that can facilitate the adsorption and activation of CO 2 , the coordinated DMF and H 2 O molecules on the pristine samples were removed (see the experimental procedures) prior to use.…”

Synergistic Interplay of Dual‐Active‐Sites on Metallic Ni‐MOFs Loaded with Pt for Thermal‐Photocatalytic Conversion of Atmospheric CO2 under Infrared Light Irradiation

“…Ni‐MOF was synthesized via a one‐step solvothermal reaction in a mixture of water and N,N‐dimethylformamide (DMF) solvent [25] . According to the results of single‐crystal X‐ray diffraction studies, [25,26] Ni‐MOF crystallizes in the trigonal crystal system of the R $${\mathrel{\mathop{{\rm { 3}}}\limits^{{\rm -}}}\ }$$ space group and exhibits a three‐dimensional (3D) network based on [Ni 3 (COO) 6 ] clusters with hexagonal 1D channels of 1.3 nm diameter (Figure 1a).…”

Constructing abundant interfaces by decorating MoP quantum dots on CoP nanowires to induce electronic structure modulation for enhanced hydrogen evolution reaction

“…6c and Table S4 (ESI †). 4,66,[70][71][72][73][74][75][76][77][78][79][80][81][82][83][84] As depicted in Fig. 6d, a current density of approximately 10 mA cm À2 can be achieved when the applied voltage is 1.54 V. The catalytic activity remained at 97.5% after continuous operation for 24 hours, as illustrated in Fig.…”