High‐Performance Photoelectrochemical Water Oxidation with Phosphorus‐Doped and Metal Phosphide Cocatalyst‐Modified g‐C₃N₄ Formation Through Gas Treatment

Abstract

Graphitic carbon nitride (g‐C3N4) has been widely explored as a photocatalyst for water splitting. The anodic water oxidation reaction (WOR) remains a major obstacle for such processes, with issues such as low surface area of g‐C3N4, poor light absorption, and low charge‐transfer efficiency. In this work, such longtime concerns have been partially addressed with band gap and surface engineering of nanostructured graphitic carbon nitride (g‐C3N4). Specifically, surface area and charge‐transfer efficiency are significantly enhanced through architecting g‐C3N4 on nanorod TiO2 to avoid aggregation of layered g‐C3N4. Moreover, a simple phosphide gas treatment of TiO2/g‐C3N4 configuration not only narrows the band gap of g‐C3N4 by 0.57 eV shifting it into visible range but also generates in situ a metal phosphide (M=Fe, Cu) water oxidation cocatalyst. This TiO2/g‐C3N4/FeP configuration significantly improves charge separation and transfer capability. As a result, our non‐noble‐metal photoelectrochemical system yields outstanding visible light (>420 nm) photocurrent: approximately 0.3 mA cm−2 at 1.23 V and 1.1 mA cm−2 at 2.0 V versus RHE, which is the highest for a g‐C3N4‐based photoanode. It is expected that the TiO2/g‐C3N4/FeP configuration synthesized by a simple phosphide gas treatment will provide new insight for producing robust g‐C3N4 for water oxidation.

Unraveling the Impact of Electrochemically Created Oxygen Vacancies on the Performance of ZnO Nanowire Photoanodes

“…The increased carrier density may be one of the reasons responsible for the improved photocurrent of reduced ZnO; however, in contrast to the large enhancement (3-fold) in photocurrent, the increase (no more than 2-fold) in Nd is fairly limited. In general, doubling or further enhancement of the photocurrent requires an increase of the Nd value over 1 order of magnitude, as already observed in nitrogen-annealed hematite, hydrogen-annealed TiO 2 , or phosphine-annealed g-C 3 N 4 . This result clearly indicates that there are may be some hidden factors that account for the improved performance of reduced ZnO.…”

Highly efficient visible light active Cu–ZnO/S-g-C3N4 nanocomposites for efficient photocatalytic degradation of organic pollutants

“…The maximum rate constant value observed for CZS-25 NC indicated that the synergistic effect between SGN, Cu, and ZnO has improved the number of active sites, and correspondingly enhanced the photocatalytic efficiency against MB dye. [56][57][58] Nonetheless, as the quantity of S-g-C 3 N 4 in CZS NCs was increased beyond 25%, the photocatalytic performance of CZS NCs consistently decreased. This effect is consistent with previous ndings, which show that as the constituent content surpasses the optimum value, the photocatalytic efficacy of the type-II nanoheterostructures decreases.…”

Construction of a hierarchical ZnIn2S4/C3N4 heterojunction for the enhanced photocatalytic degradation of tetracycline

“…Polymeric carbon nitrogen (C 3 N 4 ), a known efficient visible light responsive photocatalyst, is among the most attractive candidates due to its low cost, excellent thermal and chemical stability, and moderate band gap. [14][15][16][17][18] Nevertheless, the photocatalytic performance of pristine C 3 N 4 is still unsatisfactory due to its fairly poor active sites, limited utilization of visible light and fast recombination of charge carriers. [19][20][21] Typically, nanostructure engineering and heterojunction design are two effective methods to overcome the above drawbacks currently.…”