A Nanojunction Polymer Photoelectrode for Efficient Charge Transport and Separation

Abstract

A metal‐free photoanode nanojunction architecture, composed of B‐doped carbon nitride nanolayer and bulk carbon nitride, was fabricated by a one‐step approach. This type of nanojunction (s‐BCN) overcomes a few intrinsic drawbacks of carbon nitride film (severe bulk charge recombination and slow charge transfer). The top layer of the nanojunction has a depth of ca. 100 nm and the bottom layer is ca. 900 nm. The nanojunction photoanode results into a 10‐fold higher photocurrent than bulk graphitic carbon nitride (G‐CN) photoanode, with a record photocurrent density of 103.2 μA cm−2 at 1.23 V vs. RHE under one sun irradiation and an extremely high incident photon‐to‐current efficiency (IPCE) of ca. 10 % at 400 nm. Electrochemical impedance spectroscopy, Mott–Schottky plots, and intensity‐modulated photocurrent spectroscopy show that such enhancement is mainly due to the mitigated deep trap states, a more than 10 times faster charge transfer rate and nearly three times higher conductivity due to the nanojunction architecture.

Bandgap Engineering of Organic Semiconductors for Highly Efficient Photocatalytic Water Splitting

“…The bandgap for the nondoped system of is calculated as 1.01 eV, which underestimated the experimental value. Such results are to be expected when using a GGA level of theory such as the one employed by the PBE functional [54] and are consistent with previous literature. [55] Our analysis does not therefore make use of band structure but focuses on the charge distribution, which is expected to be reliable at this level of theory.…”

“…Such results are to be expected when using a GGA level of theory such as the one employed by the PBE functional [54] and are consistent with previous literature. Such results are to be expected when using a GGA level of theory such as the one employed by the PBE functional [54] and are consistent with previous literature.…”

“…As shown in Figure 4a, the photocurrent performance on the FAT-1.0 sample and FAT-0 shows a nearly 26 fold difference, consistent with the measured HER. [54] Photoluminescence (PL) measurements were used to compare the charge separation capability on the FAT samples using a UV laser (325 nm, Figure 4b). The peak near 420 nm is assigned to emissions from band edges involving π-conjugated states.…”

Phosphorylation of Polymeric Carbon Nitride Photoanodes with Increased Surface Valence Electrons for Solar Water Splitting

“…Therefore, the valence electron of nitrogen p z orbitals directly determines the capability of the PCN photoanode for water oxidation, but comprehensive studies on the topic are lacking, especially after phosphorylation . The use of PCN as a photoanode for solar water splitting has received increasing interesting recently, and a few approaches to enhance the performance, such as integrating and doping with metal oxides, were studied.…”

Improved Utilization of Sunlight Through the Incidence Dependence of the Photonic Stop Band: A g‐C3N4‐Embedded Fluorine‐Doped Tin Oxide (FTO) Photonic Crystal Film

“…[4,5] The optimization of light absorption and conversion, charge carrier separation and transportation are the critical factors for improving the performance of a solar energy conversion device. To this end, efforts such as doping [6,7,8] and nanostructuring the photoactive materials, [5,9] adding co-catalysts [10] or sacrificial reagent [11] have been made, and solar energy conversion devices with improved performance are therefore obtained. While an alternative strategy to pursue these improvements is using both the nature of materials and the nature of nature (the sun).…”