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Herein, we demonstrate the first example of a novel electrocatalytic hybrid system (CoTPP–PZSNT) with a push–pull motif to boost hydrogen evolution reaction (HER) activity. CoTPP–PZSNT exhibits an efficient HER activity, with overpotentials of 157 and 109 mV at 10 mA cm−2 in 1.0 M KOH and 0.5 M H2SO4 solutions, respectively. The HER performance of CoTPP–PZSNT outperforms many previously reported HER catalysts, due to efficient charge transfer between each component. [ABSTRACT FROM AUTHOR]

The as-prepared NiTAPP-NiACQ exhibits excellent long-term durability and remarkable HER performance with a low overpotential of 117 mV at 10 mA cm−2, which is quite comparable to many reported electrocatalytic HER systems. [Display omitted] To realize efficient water splitting, a highly promising hydrogen evolution reaction (HER) electrocatalyst is needed for the generation of hydrogen. Herein, we demonstrate a novel acenaphthenediimine complex-bridged porphyrin porous organic polymer (NiTAPP-NiACQ) with enriched active metal sites and hierarchical pores. The as-prepared NiTAPP-NiACQ exhibits good long-term durability and remarkable HER performance in 1.0 M KOH with a low overpotential of 117 mV at 10 mA cm−2, which is comparable to many previously reported electrocatalytic HER systems. Furthermore, a simple water-alkali electrolyzer using NiTAPP-NiACQ as the cathode requires a small cell voltage of 1.59 V to deliver a current density of 10 mA cm−2 at room temperature, along with outstanding durability. NiTAPP-NiACQ features not only a metal ion as the catalytic active center in the porphyrin core but also metal ion coordination on the anthraquinone component to promote HER performance, enabling multiple metal ions as the electrocatalytic active sites for the HER reaction. The excellent HER activity of NiTAPP-NiACQ is ascribed to a combination of mechanisms. These findings highlight the viability of porphyrin-derived porous organic polymers in energy conversion processes. [ABSTRACT FROM AUTHOR]

A novel nitrogen-rich azo-bridged metallated porphyrin POP (CoTAPP-CoTNPP) network was engineered by the combination of cobalt porphyrins with azo groups together, which exhibits an enhanced HER performance as compared to other control samples. [Display omitted] The potential of porous organic polymers (POPs) toward electrocatalytic water splitting have attracted considerable scientific attention, due to their high specific surface areas, superlative porosity and diverse electronic structures; yet it remains challenging. Herein, we report a facile synthesized novel nitrogen-rich azo-bridged metallated porphyrin POP (CoTAPP-CoTNPP) for improving the hydrogen evolution reaction (HER) activity. The incorporation of the cobalt porphyrins and the azo groups endows CoTAPP-CoTNPP with effective charge transfer efficiency and large π-conjugated porous frameworks, thus enhancing the HER performance. Origins of the excellent HER performance of the material are evaluated using a series of structural and electrochemical measurements. Remarkably, CoTAPP-CoTNPP exhibits low overpotentials of 103 and 170 mV to reach 10 mA cm−2 in acidic and alkaline media, respectively, outperforming many previously reported HER electrocatalysts. These results demonstrate the enormous potential of the as-prepared azo-linked porphyrin POP for electrocatalytic water splitting. [ABSTRACT FROM AUTHOR]

Herein, a series of g-C3N4 supported bimetallic sulfide nanostructures (Ni3S2/MoS2/ng-C3N4, n = 10, 20 and 30) was prepared by a hydrothermal method and subsequently a thermal annealing approach. Ni3S2/MoS2/20g-C3N4 with controlled composition exhibits efficient OER activity with a low overpotential of 183 mV at 10 mA cm−2, which outperforms the vast majority of sulfide OER electrocatalysts reported previously. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate a facile strategy for constructing an efficient and stable hydrogen evolution reaction (HER) catalyst, i.e. a tin porphyrin axially-coordinated 2D covalent organic polymer (SnTPPCOP). SnTPPCOP exhibits promising HER activity with a low overpotential of 147 mV at 10 mA cm−2 due to its unique structural properties, ranking among the best records reported recently. [ABSTRACT FROM AUTHOR]

Herein, a series of FeOx-MoP@MWCNT composite electrocatalysts was designed and prepared to investigate the influence of the content of FeOx on the water splitting performance. The optimized FeOx-MoP@MWCNTs-2 exhibits excellent hydrogen and oxygen evolution reaction activity while a cell voltage of 1.51 V with outstanding stability is attained, attributed to the synergistic effect of each component, as evidenced by the experimental and density functional theory results. The observed electrocatalytic activity outperforms current state-of-the-art non-precious metal electrocatalysts. [ABSTRACT FROM AUTHOR]

Herein, we report a novel graphene oxide (GO) nanohybrid covalently functionalized by covalent organic polymer (COP) based on porphyrin (GO-TPPCOP), as the optical limiter and hydrogen evolution reaction (HER) electrocatalyst. The GO-TPPCOP nanohybrid exhibits markedly enhanced optical limiting and HER activity over that of TPP, GO and TPPCOP alone. More importantly, the optical limiting property and HER activity of GO-TPPCOP nanohybrid are comparable to the state-of-the-art activity of materials from some previous reports. The possible mechanisms of optical limiting and HER are explored by various means, including UV-Vis absorption, fluorescence, photocurrent, electrochemical impedance spectra and Raman spectroscopic techniques. It is demonstrated that the synergistic effect and charge transfer between GO and TPPCOP are important factors in determining its optical limiting and HER performances. These results demonstrate a new strategy to design and develop functional nanohybrids for efficient optical limiting and HER activity by the covalent linkage of GO with COPs. [ABSTRACT FROM AUTHOR]

Integration of metalloporphyrin moieties into the porous organic polymer (POP) framework via conjugated linkages can contribute to the hydrogen evolution reaction (HER) performance, due to the interpenetrated macrocyclic hollow channels, and the well-defined catalytic sites. Herein, a porous cobalt porphyrinic network (CoTPP-POP) with benzene linkages was designed and prepared for water reduction. CoTPP-POP exhibits the excellent HER performance with a low overpotential (150 mV at 10 mA cm−2), good long-term durability and remarkable Faradaic efficiency in acidic medium. The HER performance of CoTPP-POP is comparable to many previously reported non-noble electrocatalysts. This contribution demonstrates a facile approach to design other advanced systems for energy-related electrocatalysis. • A porous cobalt porphyrinic network (CoTPP-POP) with benzene linkages was designed. • CoTPP-POP exhibits relative low overpotential of 150 mV to reach 10 mA cm−2. • The effective HER activity is ascribed to a combination of mechanisms. [ABSTRACT FROM AUTHOR]

Covalent organic polymers have attracted much attention due to their high specific surface area, superlative porosity, and diversity in electronic structure. Herein, a novel porous cobalt-porphyrin-based covalent organic polymer (CoCOP) is fabricated through the Schiff-base condensation reaction, which is used as a difunctional electrocatalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The CoCOP possesses a high surface area and strong synergistic effect between the cobalt-porphyrins and the C N groups, resulting in efficient HER and OER performances. The CoCOP required relatively low overpotentials for both HER (121 mV to reach 1.0 mA cm−2 and 310 mV to reach 10 mA cm−2) and OER (166 mV to reach 1.0 mA cm−2 and 350 mV to reach 10 mA cm−2) in alkaline media. This work may provide a new idea for the design of non-noble metal-based coordination polymers with excellent structure and high electrocatalytic performance. [ABSTRACT FROM AUTHOR]

In this contribution, two constituent-tunable metallophthalocyanine covalent organic polymers (MPc-COPs) covalently attached to graphene oxide (GO-PcP 1 and GO-PcP 2) were rationally designed and fabricated for optoelectronics and electrocatalysis. The resultant GO-PcP nanohybrids exhibit markedly enhanced nonlinear optical and optical limiting performances over those of their components and physical mixtures at 532 nm in the nanosecond pulse range. The optical nonlinearity can be further optimized by tuning the linkage type between the four-branched tetraamine metallophthalocyanine units. The hydrogen evolution reaction (HER) is investigated by linear sweep voltammetry in a 0.5-M H 2 SO 4 aqueous solution. Under optimal conditions, the overpotentials needed to reach 1 mA cm−2 are measured as 237 and 210 mV for GO-PcP 1 and GO-PcP 2, respectively, which places GO-PcP 2 as the best metallophthalocyanine polymer-based HER catalyst to be reported in the literature. The improved performances were ascribed to the positive synergistic effects between MPc-COPs and GO. Notably, the present study introduces a new strategy for the precise preparation of MPc-COP-based nanomaterials while exploring their applications to develop highly efficient optical limiters and electrocatalysts. [ABSTRACT FROM AUTHOR]

• Porphyrin coordination polymer (TiCP-PCP) decorated Co 1−x S composite was designed. • The introduction of TiCP-PCP provides abundant active sites for oxygen evolution. • The composite exhibits excellent electrocatalysis with ultralow overpotential. • The improved electrocatalysis is assigned to a combination of mechanisms. It is very imperative to develop cost-effective nonprecious-metal-containing materials with efficient oxygen evolution reaction (OER) activity. Herein, a series of novel composite catalysts (TiCP-PCP@Co 1−x S) by coupling Co 1−x S with porphyrin based porous titanium coordination polymer (TiCP-PCP) was designed and prepared, and was characterized by different spectroscopic techniques. The introduction of TiCP-PCP can significantly increase the number of active sites and tune the electronic structure of Co 1−x S to reach affluent surface Co3+ active sites center for boosting OER intrinsic activity. The present study indicates that there is an optimum concentration of TiCP-PCP in the composites to maximize OER performance; the optimized 0.2TiCP-PCP@Co 1−x S composite with 20 wt% TiCP-PCP exhibits the best OER activity with a low overpotential of 157 mV at a current density of 10 mA cm−2 and excellent long-term stability in alkaline solution. The OER performance of 0.2TiCP-PCP@Co 1−x S outperforms state-of-the-art nonprecious-metal catalysts (i.e. IrO 2 and RuO 2) and most previous reported cobalt-based catalysts. [ABSTRACT FROM AUTHOR]

Herein, a novel porous titanium coordination polymer (TiCP-PCP) with push-pull motif is prepared through the transesterification reaction of catechol porphyrin with titanium tetraisopropoxide. TiCP-PCP demonstrates efficient electrocatalytic activity toward HER/OER with prominent electrochemical durability in acid/basic medium. Surprisingly, TiCP-PCP requires relatively low overpotentials of 339 and 310 mV to reach a catalytic current density of 10 mA cm−2 for HER and OER, respectively. Based on experimental and theoretical results, the improved electrocatalytic performances for TiCP-PCP in comparison with those of TPP and TiO 2 are ascribed to efficient charge transfer and positive synergistic effect, stemming from the interactions between porphyrin units and Ti entities. This work can be readily extended to a wide range of porous coordination polymer-based electrochemical devices and catalysts design. A novel porous titanium coordination polymer with push-pull motif was designed and prepared through the transterification reaction of catechol porphyrin with titanium tetraisopropoxide. TiCP-PCP demonstrated efficient electrocatalytic activity toward HER/OER with prominent electrochemical durability in acid/basic medium. Image 1 • A novel porous titanium coordination polymer with push-pull motif was designed. • This polymer can provide abundant active sites for hydrogen and oxygen evolution. • The prepared polymer exhibited excellent electrocatalysis. • The improved electrocatalysis was assigned to a combination of mechanisms. [ABSTRACT FROM AUTHOR]

Benefiting from the strong electronic interactions between the triazine unit and the CoTAPP moiety, a standard current density at 10 mA cm−2 is obtained for CoTAPPCC with a smaller overpotential of 150 mV in acid, which is comparable to or better than the best records reported previously. [Display omitted] Hydrogen production obtained by electrocatalytic water splitting exhibits great promise in addressing both energy shortage and environmental contamination. Herein, we prepared a novel cobalt porphyrin (CoTAPP)-bridged covalent triazine polymer (CoTAPPCC) by covalently linking CoTAPP with cyanuric chloride (CC) for catalytic hydrogen evolution reaction (HER). Both experimental techniques and density functional theory (DFT) calculations were used to evaluate the correlation of HER activity with molecular structures. Benefiting from the strong electronic interactions between the CC unit and the CoTAPP moiety, a standard current density at 10 mA cm−2 is obtained for CoTAPPCC with a low overpotential of 150 mV in acid, which is comparable to or better than the best records reported previously. Additionally, a competitive HER activity in basic medium is obtained for CoTAPPCC. The strategy reported herein is valuable for designing and developing porphyrin-based efficient HER electrocatalysts. [ABSTRACT FROM AUTHOR]

Rational design of efficient hydrogen evolution reaction (HER) electrocatalysts, constructed with earth-abundant elements, is critical for developing sustainable alternative energy sources. Herein, two phosphonitrilic-bridged metal porphyrin porous covalent organic polymers (COPs) were developed for HER. Compared to CoTPP-PCTCOP, NiTPP-PCTCOP exhibits relative low overpotentials of 140 to reach 10 mA cm−2 for HER in alkaline medium, which is comparable to many previously reported state-of-the-art electrocatalysts. The enhanced HER activity of NiTPP-PCTCOP is associated with its chemical composition and special push-pull structure. Long-term stability analysis of NiTPP-PCTCOP shows that the current density exhibits no obvious deactivation over a long time test. This work demonstrates an effective technique to develop promising HER electrocatalysts, highlighting its advantages by combing phosphonitrilic chloride trimer with metal porphyrins. [Display omitted] • Two phosphonitrilic-bridged metal porphyrin COPs were developed for HER. • NiTPP-PCTCOP exhibits relative low overpotentials of 140 to reach 10 mA cm−2. • The effective HER activity is associated with its special push-pull structure. [ABSTRACT FROM AUTHOR]

• Tunable oxygen reduction reaction properties is achieved by varying the electrolyte pH. • An A3B-type cobalt porphyrin-coated carbon black is designed as the catalyst. • Five electrolytes with pH values spanning from 0.7 to 13.7 are studied. • The composite exhibits the most positive potentials and the lowest Tafel slope at pH13.7. • Poor activity but high selectivity for 4-electron ORR is obtained at pH3.7. Understanding the pH-dependent mechanism of metalloporphyrin-based composite electrocatalystic oxygen reduction reactions (ORRs) can provide the basis for rational porphyrin molecular design. Tunable ORR properties of a cobalt porphyrin-based composite catalyst aFP-TCoP/C is accomplished by adjusting the electrolyte pH values spanning from 0.7 to 13.7. The composite performs the best ORR reactivity in the pH13.7 electrolyte, exhibiting the most positive characterized potentials (the ORR reduction potential E ORR of 0.76 V and the half-wave potential E 1/2 of 0.80 V) and the smallest Tafel slope of 43.1 mV dec−1. Whilst the sample with the pH3.7 electrolyte displays quite negative reduction potentials and a large Tafel slope, it exhibits an electron transfer number of 3.84, which indicates a nearly 4-electron transfer selectivity. The findings provide a practical protocol for regulating the catalytic reactivity and selectivity of ORRs by adjusting the components of electrolytes. [Display omitted] [ABSTRACT FROM AUTHOR]