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The ability to molecularly engineer materials may be one of the most powerful tools in favor of high performing heterogeneous catalysts. Porous organic polymers stand out as photocatalysts due to their high chemical stability, outstanding optoelectronic properties and their easy and tunable syntheses. In photocatalysis, the insertion of photosensitizing π-extended molecules into a molecularly well-defined donor-acceptor junctions is supposed to increase the cata-lytic activity, but yet remain experimentally underdeveloped. Here, we present a pyrene-based Covalent Triazine Framework (CTF) synthesized through a polycondensation approach, which was designed to contain a molecularly defined pyrene-triazine-bipyridine donor-acceptor-acceptor triad as the repetition unit of the CTF. The CTF is an efficient photocatalyst for hydrogen evolution from water reaching a production rate of 61.5 mmolH2/h/gcat. Moreover, the same CTF can easily be used as porous macroligand for an organometallic Rh complex to efficiently catalyze the carbon dioxide photoreduction into formic acid under visible light.

An iridium pincer complex {p‐KO‐C6H2‐2,6‐[OP(t‐Bu)2]2}Ir(C2H4) is immobilized in a propyl bromide‐functionalized microporous polymer network using the concepts of surface organometallic chemistry. The support material enables the formation of isolated active metal sites embedded in a chemically robust and highly hydrophobic environment. The catalyst maintained high porosity and – without prior activation – exhibited high activity in the continuous‐flow dehydrogenation of cyclohexane at elevated temperatures. The catalyst shows a stable performance for at least 7 days, even when additional H2O was co‐fed, owing to its hydrophobic nature.

Photocatalytic water-splitting provides a way to store solar energy as hydrogen gas, and hence, is an attractive alternative to energy-intensive electrolysis of water. Microporous polymer networks are an interesting class of heterogeneous photocatalysts due to the chemical modularity of their optically active backbone and their guest-accessible pore-structure. Photocatalytic action depends on efficient separation of photoexcited electron-hole pairs, and recently, it was discovered that this separation can be improved by incorporation of donor-acceptor motifs into the polymer backbones. While there are many examples of electron donors, there is little variety in electron acceptor motifs. Here, we present a series of microporous donor-acceptor networks that contain electron-deficient boron moieties (triarylborane) as the electron acceptors and sulfur moieties (thiophene) as the donors. Under sacrificial conditions, these sulfur- and boron-containing polymers (SBPs) show rates of hydrogen evolution up to 113.9 mmol h-1 g-1. Conventionally used platinum co-catalyst does not contribute meaningfully to the photocatalytic action. Instead, palladium that is incorporated during the stage of polymer synthesis acts as the co-catalyst.

Black phosphorus (BP) as a layered two-dimensional (2D) semiconductor material with a tunable band gap has attracted growing attention for promising applications in diverse fields including biotechnology owing to its excellent physical and chemical properties. In this study, BP crystals were synthesized using a chemical vapor transport method and exfoliated into BP nanosheets in deoxygenated water or hexane. Next, monodisperse Au nanoparticles that were synthesized using a surfactant-assisted chemical reduction method were assembled on exfoliated BP nanosheets hexane to yield BP/Au nanocomposites. The photothermal antibacterial and antibiofilm activities of BP nanosheets and BP/Au nanocomposites were investigated against Enterococcus faecalis, a pathogenic biofilm-forming bacterium, by studying the photothermal effect and bacterial growth curve and using colony counting and live/dead fluorescence staining methods under near-infrared (NIR) light irradiation. Thanks to the higher photothermal conversion efficiency of BP/Au nanocomposites than that of bare BP nanosheets under NIR light irradiation, they destructed the bacterial cell membrane more efficiently than bare BP with the biofilm inhibition rate of 58%. It should be noted that this is the first study on the antibacterial and antibiofilm activity of BP/Au nanocomposites via a photothermal process under NIR light irradiation. This work shows the potential of BP/Au nanocomposites in fighting against pathogenic bacteria and paves the way for the exploration of antibacterial platforms based on the biocompatible 2D semiconductor BP.

A novel ternary nanocomposite, mesoporous graphitic carbon nitride/black phosphorus-AgPd (denoted mpg-CN/BP-AgPd), was successfully fabricated by assembling the as-prepared AgPd alloy nanoparticles (NPs) on mesoporous graphitic carbon nitride/black phosphorus (mpg-CN/BP) binary composites. This novel nanocomposite comprises a heterojunction support material formed by two distinct nonmetallic semiconductors (mpg-CN and BP) with adaptable band gaps and edge voltages, providing enhanced catalytic activity to AgPd alloy NPs in hydrogen generation from the methanolysis of ammonia borane (AB) compared to its single components under the blue light-emitting diode (LED) light illumination. The yielded mpg-CN/BP-AgPd ternary nanocomposites were characterized by many advanced analytical techniques (transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy (PL), time-resolved spectroscopy, inductively coupled plasma-mass spectroscopy (ICP-MS), and fourier transform infrared (FTIR), and then they were tested as catalysts in hydrogen generation from the methanolysis of AB at room temperature. Several parameters such as the effect of mpg-CN/BP ratio, alloy composition, and type of the light source were studied to optimize the catalytic activity of the mpg-CN/BP-AgPd nanocomposites in the methanolysis of AB. The best catalytic activity of mpg-CN/BP-AgPd nanocomposites was obtained using an mpg-CN/BP ratio of 5/1 (wt/wt) and Ag50Pd50 alloy composition under the blue LED illumination at room temperature. The activity of the ternary nanocomposites was further enhanced by the acetic acid treatment, and a high initial turnover frequency of 43.7 mol(H2) mol(catalyst)-1 min-1 was reported. Besides their high catalytic activity, the mpg-CN/BP-AgPd nanocomposites were reusable catalysts in the methanolysis of AB. This study also included detailed kinetics of AB methanolysis catalyzed by mpg-CN/BP-AgPd nanocomposites.

Photocatalysis using semiconductor materials to conduct chemical reactions more efficiently with the aid of sunlight irradiation is foreseen as a promising solution to combat the energy and environmental pollution crisis that the world is facing at present. Finding a suitable semiconductor material that harvests a large portion of the sunlight spectrum with high photocatalytic efficiency lies in the heart of photocatalysis. In this regard, black phosphorus (BP), a rising star two-dimensional (2D) semiconducting material, has recently been regarded as an abundant, nontoxic, metal-free, and cheap photocatalyst with a suitable bandgap and broad light absorption ability. In this chapter, after the introduction of the general properties and synthesis of BP, the photocatalytic efficiency of BP and BP-based composites in energy and environmental applications are summarized.

Black phosphorus (BP) is for the first time employed as a metal-free, heterogeneous photoredox catalyst for the direct C-H arylation of heteroarenes with aryl diazonium salts. The arylated heteroarenes are obtained in moderate to good yields under visible-light illumination, and the protocol is shown to be applicable for the scale-up synthesis.

We report herein the fabrication of a novel ternary nanocomposite of mesoporous graphitic carbon nitride/black phosphorus-gold nanoparticles (mpg-CN/BP-Au) and its catalytic performance in the photocatalytic hydrogen evolution reaction (HER) and electrochemical detection of paracetamol. The photocatalytic hydrogen production rate of mpg-CN/BP-Au nanocomposite (1024 µmol g−1 for 8 h) is compared with mpg-CN, mpg-CN/BP and mpg-CN/Au in the presence of triethanolamine (TEOA) as a hole scavenger under the visible light. In addition to the photocatalytic HER application, as-prepared mpg-CN/BP-Au nanocomposite was deposited on modified glassy carbon electrode (mpg-CN/BP-Au/GCE) and for the first time tested for the detection of paracetamol (PA). Under the optimum conditions, linear range of paracetamol detection was found to be in the range of 0.3–120 µM with a detection limit of 0.0425 µM. mpg-CN/BP-Au/GCE provided higher electrocatalytic activity than pristine mpg-CN and all other tested binary nanocomposites. The enhanced photo- and electrochemical activity of mpg-CN/BP-Au/GCE are attributed to formation of heterojunction between BP and mpg-CN materials. Additionally, Au nanoparticles increase the rate of adsorption of mpg-CN/BP due to the excellent electrical properties and spillover effect. We believe that the presented design and catalysis of the ternary nanocomposite will pave a way in many photo- and electrochemical applications.

Development of an economical, well-defined and efficient electrocatalyst having a potential to replace Pt/C is crucial for oxygen reduction reaction (ORR). In this respect, we report herein one-pot wet-chemical protocol for the composition-controlled synthesis of monodisperse CuAg alloy nanoparticles (NPs) and their composition-dependent electrocatalytic activities in ORR for the first time under an alkaline condition. The presented synthetic procedure yields CuAg NPs that exhibit monodisperse size distribution with an average particle diameter of ∼8 nm. Almost homogenous CuAg alloy formation is proved by using many advanced analytical techniques despite the considerable lattice mismatch between Cu and Ag. At all compositions investigated, the ORR activities of CuAg electrocatalysts are found to be significantly higher than monometallic Ag NPs. Improved ORR kinetics of CuAg alloy NPs are demonstrated by Tafel slopes (85 mV/dec for Cu30Ag70, 84 mV/dec for Cu40Ag60 and 78 mV/dec for Cu60Ag40 which are all smaller than that of monometallic Ag (113 mV/dec). Electrochemical impedance measurements support these findings and represent that charge transfer resistance strongly depends on composition of CuAg electrocatalyst. The ORR activity and surface analysis results put Cu40Ag60 forward since Cu oxidation is suppressed in Cu40Ag60 NPs, caused by Ag enhancement in the surface.