Photocatalytic oxygen evolution from low-bandgap conjugated microporous polymer nanosheets: a combined first-principles calculation and experimental study

Abstract

Nanostructured semiconducting polymers have emerged as a very promising class of metal-free photocatalytic materials for solar water splitting. However, they generally exhibit low efficiency and lack the ability to utilize long-wavelength photons in a photocatalytic oxygen evolution reaction (OER). Here, based on first-principles calculations, we reveal that the two-dimensional (2D) aza-fused conjugated microporous polymer (aza-CMP) with a honeycomb network is a semiconductor with novel layer-dependent electronic properties. The bandgap of the as-synthesized aza-CMP nanosheets is measured to be 1.22 eV, suggesting that they can effectively boost light absorption in the visible and near infrared (NIR) region. More importantly, aza-CMP also possesses a valence band margin suitable for a photocatalytic OER. Taking advantage of the 2D layered nanostructure, we further show that the exfoliated ultrathin aza-CMP nanosheets can exhibit a three-fold enhancement in the photocatalytic OER. After deposition of a Co(OH) cocatalyst, the hybrid Co(OH)/aza-CMP photocatalyst exhibits a markedly improved performance for photocatalytic O evolution. Furthermore, first-principles calculations reveal that the photocatalytic O evolution reaction is energetically feasible for aza-CMP nanosheets under visible light irradiation. Our findings reveal that nanostructured polymers hold great potential for photocatalytic applications with efficient solar energy utilization.

A C5N2 Nanoparticle Based Direct Nucleus Delivery Platform for Synergistic Cancer Therapy

“…The enhanced cell uptake of C 5 N 2 -DOX NPs could be attributed to the additional supramolecular interactions between C 5 N 2 NPs and the cell membrane.Next, the nucleus-entry capacity of C 5 N 2 -DOXNPs with different DOX loading amounts (see Figures S16 and S17 for the morphology of the C 5 N 2 -DOX NPs) was investigated in detail. [19] Furthermore,a fter loading with positively charged DOX, the zeta potential of C 5 N 2 NPs was increased from À24.7 to + 32.1 mV (see Figure S16 A), indicating that electrostatic interactions between C 5 N 2 NPs and DOX also endow them with ah igh DOX loading rate.M eanwhile,w ith pH-/photoresponsive DOX release ( Figure 4B), C 5 N 2 NPs have great potential in drug delivery.Considering their strong absorbance in the NIR region (see Figure S18 A,B), C 5 N 2 NPs might possess aphotothermal effect. C 5 N 2 NPs had amaximum DOXloading rate of 3400 %in weight ( Figure 4A), which to the best of our knowledge is the largest of all reported nanocarriers.T he high DOXl oading rate might be due to the abundant micropores and large specific surface area of C 5 N 2 NPs.…”

“…C 5 N 2 NPs had amaximum DOXloading rate of 3400 %in weight ( Figure 4A), which to the best of our knowledge is the largest of all reported nanocarriers.T he high DOXl oading rate might be due to the abundant micropores and large specific surface area of C 5 N 2 NPs. [19] Furthermore,a fter loading with positively charged DOX, the zeta potential of C 5 N 2 NPs was increased from À24.7 to + 32.1 mV (see Figure S16 A), indicating that electrostatic interactions between C 5 N 2 NPs and DOX also endow them with ah igh DOX loading rate.M eanwhile,w ith pH-/photoresponsive DOX release ( Figure 4B), C 5 N 2 NPs have great potential in drug delivery.Considering their strong absorbance in the NIR region (see Figure S18 A,B), C 5 N 2 NPs might possess aphotothermal effect. Thetemperature of solutions of C 5 N 2 NPs rose by 21 8 8Cupon irradiation with 808 nm light ( Figure 4C).…”

“…[19] Thus,thermodynamically,t he unique electronic structure of C 5 N 2 NPs might allow them to generate singlet oxygen ( 1 O 2 )u nder illumination (see Figure S19 for adetailed discussion). [19] Thus,thermodynamically,t he unique electronic structure of C 5 N 2 NPs might allow them to generate singlet oxygen ( 1 O 2 )u nder illumination (see Figure S19 for adetailed discussion).…”

“…Zuschriften (single layer), and have been employed in photocatalysis because of their impressive carrier mobility. [19] Thus,thermodynamically,t he unique electronic structure of C 5 N 2 NPs might allow them to generate singlet oxygen ( 1 O 2 )u nder illumination (see Figure S19 for adetailed discussion). Under 650 nm laser irradiation, the continual fluorescence decrease of 1,3-diphenylisobenzofuran (DPBF,w hose fluorescence decreases when 1 O 2 is produced) in as olution of C 5 N 2 NPs and the good photostability of C 5 N 2 NPs showed their great potential in PDT (see Figure S20 A,B).…”

2D Polymers as Emerging Materials for Photocatalytic Overall Water Splitting

“…Poly‐ p ‐phenylene (PPP) synthesized via Ni‐catalyzed cross‐coupling reaction from 1,4‐dibormobenezene was the first conjugated polymer that was able to generate H 2 using amines as sacrificial electron donors under ultraviolet‐light irradiation. Inspired by this seminal work, various polymer photocatalysts with increasingly complicated structures and morphologies are since then developed . Polymers are generally comprised of naturally abundant elements such as C, H, and N. They are very promising candidates as low‐cost and easily processable photocatalysts for solar‐driven water splitting.…”