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Metalloporphyrins have exhibited excellent electrocatalytic activities for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). In order to improve the efficiency and conductivity, these molecular catalysts need to be immobilized on conductive electrode materials. Herein, a facile "one-pot" strategy was developed to coat a covalent metalloporphyrin polymer on a carbon nanotube (CNT) as bifunctional catalysts [denoted as MTIPP@CNTs, H

Immobilizing catalysts on supports is considered to be one of the promising methods for synthesizing heterogeneous catalysts. Herein, we employed a simple one-pot method to obtain the metalloporphyrin modified carbon nanotubes (ZnTImP-CP/CNTs), using 1,4-bis(bromomethyl)-benzene (BBMB) and zinc 5,10,15,20-tetrakis(4-(imidazole)phenyl)porphyrin (ZnTImP) as monomers. With the Lewis acid sites (Zn-porphyrin) and nucleophilic groups (Br−), this composite material has displayed excellent activity and stability for catalyzing the chemical fixation of CO2 to synthesize value-added cyclic carbonates. The remarkable performance of ZnTImP-CP/CNTs is not only due to the synergy of the Lewis acid and base but also to the large specific surface area.

As S-donor metalloligands, the dithiolato [NiN2S2] complexes are employed to synthesize the bimetallic model of the active site of [NiFe]-Hydrogenases ([NiFe]-H2ases). In this work, three [NiN2S2] complexes were used to react with [NiCl2(PNP)] (PNP = (Ph2PCH2)2NCH3), respectively, to find out the influences of [NiN2S2] ligands on the structure and property of model complexes. It’s interesting to find dianion [Ni(phma)]2− (H4phma = N,N'-1,2-phenylenebis(2-mercaptoacetamide)) and [Ni(ema)]2− (H4ema = N,N'-1,2-ethylenebis(2-mercaptoacetamide)) could afford the desired dinuclear models [Ni(phma)(μ-S,S′)Ni(PNP)] (1) and [Ni(ema)(μ-S,S′)Ni(PNP)] (2), while the reaction of neutral [Ni(bme-dach)] (bme-dach = N,N′-bis-2-methyl-mercaptopropyl-1,4-diazacycloheptane) only yielded a trinuclear complex [Ni{Ni(bme-dach)(μ-S,S′)}2][BF4]2 (3). The structures of these complexes have been carefully characterized by NMR, high resolution mass spectrometry, elemental analysis, and X-ray diffraction structure analysis. As the model of [NiFe]-H2ases, complex 1 could electrocatalyze H2 evolution with a rate constant of 9.35 × 103 M−1 s−1 in the presence of CH3COOH.

Structural and functional biomimicking of the active site of [NiFe]-hydrogenases can provide helpful hints for designing bioinspired catalysts to replace the expensive noble metal catalysts for H2 generation and uptake. Treatment of dianion [Ni(phma)]2− [H4phma = N,N'-1,2-phenylenebis(2-mercaptoacetamide)] with [NiCl2(dppp)] (dppp = bis(diphenylphosphino)propane) yielded a dinickel product [Ni(phma)(μ-S,S')Ni(dppp)] (1) as the model complex relevant to the active site of [NiFe]-H2ases. The structure of complex 1 has been characterized by single-crystal X-ray analysis. From cyclic voltammetry and controlled potential electrolysis studies, complex 1 was found to be a moderate electrocatalyst for the H2-evoluting reaction using ClCH2COOH as the proton source.

The fabrication of efficient and convenient photocatalytic H2 evolution systems is a fascinating research topic in the field of solar energy conversion. A ternary self-assembled photocatalytic H2 evolution system was fabricated through supramolecular host-guest chemistry. The system consisted of the H2 evolution catalyst [Co(dmgH)2 (4-ppy)2 ]NO3 (1; dmgH2 =dimethylglyoxime, 4-ppy=4-phenylpyridine) and the photosensitizer Eosin Y (EY) assembled with the macrocyclic compound cucurbit[7]uril (CB[7]) to form the 1@CB[7]/EY complex through inclusion and exclusion interactions, respectively. The synchronous self-assembly drives an orthogonal arrangement of the 1@CB[7]/EY system. The inclusion complex 1@CB[7] was successfully characterized by 1 H NMR spectroscopy and single-crystal XRD. The exclusion process of CB[7] with EY was identified by NMR titration and the optimized geometry of the exclusion structure was determined by DFT calculations. The use of CB[7] resulted in a 6-fold increase in turnover number, a 3-fold increase in turnover frequency, and a 3-fold extension of lifetime for photocatalytic H2 evolution as compared with the system in the absence of CB[7]. The improvement of the light-driven H2 evolution activity was ascribed to the ability of CB[7] to link the photosensitizer and catalyst.

Nanostructuring and metal-support interactions have been explored as effective methods to improve the electrocatalytic activity in heterogeneous catalysis. In this study, we have fabricated ultrasmall Ru nanoparticles (NPs) dispersed on S-doped graphene (denoted as Ru/S-rGO) by a facile "one-pot" procedure. The experimental results indicated that both the S doping and moderate degree of oxidization of GO can induce the formation and high dispersion of the ultrasmall Ru NPs with larger electrochemically active surface areas for exposing more active sites. Metal-support interaction between S-doped graphene and Ru NPs was observed from the X-ray photoelectron spectroscopy and electronic charge-difference studies. It resulted in the decrease in the electron density of Ru, which facilitated electron release from H2O and H-OH bond breakage. The results of density functional theory calculation confirmed that the S-dopants could reduce the energy barrier for breaking the H-OH bond to accelerate water dissociation during the alkaline hydrogen evolution reaction (HER). At a current density 20 mA cm-2, the lowest overpotential of 14 mV, superior to that of Pt/C in alkaline solution, was observed for Ru/S-rGO-24. The observed lowest value of overpotential was because of the ultrasmall size, high dispersion, and metal-support interaction. This work provides a simple and effective method in designing advanced electrocatalysts for the HER in an alkaline electrolyte.

The fabrication of efficient and convenient photocatalytic H