Polymeric Donor–Acceptor Heterostructures for Enhanced Photocatalytic H₂ Evolution without Using Pt Cocatalysts

Abstract

Polymeric carbon nitride (CN) is apromising material for photocatalyticw ater splitting.H owever,C Ni ni ts pristinef orm tends to show moderate activityd ue to fast recombinationo ft he charge carriers.T he design of efficient photocatalytic system is therefore highly desired, but it still remains ag reat challenge in chemistry.I nt his work, ap yrene-based polymer able to serve as an electron donor to accelerate the interface chargec arrier transfer of CN is presented. Thec onstruction of donor-acceptor (D-A) heterojunction was confirmed to significantly restrain the charger ecombination and, thus, improvet he proton reduction process. Thiss tudy providesapromising strategy to achieve solar H 2 production in an efficient and lowcost manner.

Chorismate- and isochorismate converting enzymes: versatile catalysts acting on an important metabolic node

“…117 These calculations support the proposed molecular mechanisms and suggest further amino acid residues outside of the active site that may play a key role in the selectivity for one distinct molecular mechanism (hydrolysis or arene oxide). 24,50,117 The respective amino acid residues were also detected as a correlation pair in bioinformatic analysis of the different chorismatase types (see Section 8.3) but ruled out for a role in product formation based on their distance to the active site. 50,117 8.3.…”

“…This assumption is supported by experimental and theoretical data. 24,47,50 10.2. The C2/C4-hydroxyl group is important for product formation From structural data and molecular modelling studies it is likely that the pseudo-diaxial conformation of chorismate is a prerequisite for catalysis in chorismate-converting enzymes.…”

“…The pericyclic reactions catalysed by SPR enzymes, the lyase reaction of MST enzymes, and the reactions catalysed by chorismatases require a pseudo-diaxial conformation of (iso)chorismate, for which the enzymes are assumed to be selective. 24,25,29,30,54,[71][72][73][74][75]117 In all these cases, the position of the enolpyruvyl tail is essential for product formation and determines the molecular mechanism and the product selectivity in a complex interplay with polar and/or charged amino acid residues in the active site. 7,19,21,47,100 Consequently, if the enolpyruvyl side chain is of general importance for product formation and (iso)chorismate has a pseudo-diaxial conformation, the C2/C4-hydroxyl group as its counterpart is likewise of general importance for product formation.…”

“…Nevertheless, the rate-limiting step of the reactions, including their enzymatic counterparts, is still under discussion. [22][23][24][25][26] Hilvert and co-workers determined that the thermal stability of chorismate at 60 1C is higher than the thermal stability of isochorismate. 18,19,21 Comparable findings were obtained by us with chorismate and isochorismate at 25 1C; however, this study further suggested that the half-life time strongly depends on the purity of the compounds.…”

Electronic Structure Engineering of Carbon Nitride Materials by Using Polycyclic Aromatic Hydrocarbons

“…Moreover, their optical properties (absorption coefficient and high fluorescence quantum yields) alongside their electron‐donating nature make them very attractive molecules for the construction of D–A polymers . Specifically, the combination with electron‐poor polymers, such as CN, can significantly enhance the charge separation and overall photocatalytic activity …”