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Photoelectrochemical (PEC) water splitting is one of the most desirable techniques to harvest clean chemical energy from abundant solar energy. However, the anodic half reaction, i.e., water oxidation, is complicated due to the involvement of multiple electrons in this process. Herein, stable WO 3 nanoblocks with the monoclinic phase have been modified by the incorporation of hexagonal boron nitride quantum dots (h-BNQDs) to improve the photogenerated electron−hole separation and additionally to hinder the charge recombination process. The photocurrent density (J) value for the modified WO 3 photoanode by incorporation of BNQDs has been found to be 1.63 mA/cm 2 at the potential of 1.23 V RHE , which is approximately 2.4-fold higher than the bare WO 3 photoanode. The enhancement in photocurrent density is mainly due to the hole extraction property of BNQDs on the surface of the WO 3 nanoblocks. A 2-fold increment in photogenerated charge carrier density (N D ) value has been achieved due to better charge separation of electron−hole pairs in the modified system, confirmed by the Mott−Schottky (MS) plot. The present work demonstrates a unique, low-cost strategy for enhancement of PEC water oxidation by modification of the photoanode with hole extracting agents.

Photoelectrochemical (PEC) water oxidation, a desirable strategy to meet future energy demands, has several bottlenecks to resolve. One of the prominent issues is the availability of charge carriers at the surface reaction site to promote water oxidation. Of the several approaches, metal dopants to enhance the carrier density of the semiconductors, is an important one. In this work, we have studied the effect of In-doping on monoclinic WO 3 nanoblocks, growing vertically over fluorine-doped tin oxide (FTO) without the aid of any seed layer. X-ray photoelectron spectroscopy (XPS) data reveals that In 3 + ions are partially occupying the W 6 + ions in In-doped WO 3 photoanode. In 3 + ions are offering better performance by adding additional charge carriers for amplifying the expression of the number of carriers. The maximum current density value of 2.18 mA/cm 2 has been provided by the optimized In-doped WO 3 photoanode with 3 wt% indium doping at 1.23 V vs. RHE, which is~3 times higher than that of undoped monoclinic WO 3 photoanode. Mott-Schottky (MS) analysis reveals charge carrier density (N D) for In-doped WO 3 photoanode has been enhanced by a factor of 3. An average Faradic yield of~90 percent has been achieved which can serve as a model system using In 3 + as a dopant for an inexpensive and attractive method for enhanced WO 3 based PEC water oxidation.

No abstract

Phosphorus nitride dots (PNDs) as a metal-free and versatile support over host of metal oxide-based photoelectrochemical (PEC) water oxidations are reported. PNDs have the ability to form various heterojunctions by...

The assembly of MXene nanosheets into a hydrogel framework is key to their grand success in practical applications. However, the scalable realization of such stable structures is challenging and requires critically high dispersion concentration for gelation. Herein, a simple yet highly controllable approach for the development of 2D and 3D monolithic hydrogels of MXene via electro‐tunable ordered assembly is reported. Directional electrophoretic drag of MXene and their gelation by voltage‐controlled in situ released ions at the electrode interface gives rise to stable hydrogels with tunable sheet orientations. Nanosheets can be arranged in‐plane or out‐of‐plane depending on the parallel or radial field created by customized electrode assembly. Further, the gelation rate can be easily regulated by the applied potential to achieve self‐standing hydrogel films in a few tens of seconds. The 2D hydrogels display excellent supercapacitive performance of 395 F g−1 at 2 mV s−1 with high retention of 42% at 5000 mV s−1. In another customized application, the 3D‐monolithic MXene hydrogel displays outstanding performance as a solar‐thermal evaporator on behalf of its vertical sheet orientations, showing an excellent evaporation rate of 1.91 kg m−2 g−1. This simple, fast, scalable, and sheet orientation‐controlled assembly can pave the way for future development of MXene hydrogels and beyond.

No abstract

Copper tetraphenylporphyrin tetrasulfonic acid (Cu-Por) metal complex has been anchored over graphitic carbon nitrides (GCN) sheets by electrostatic interaction. The incorporation of photosensitizer through π-π interactions has greatly enhanced the...