WX_y/g‐C₃N₄ (WX_y=W₂C, WS₂, or W₂N) Composites for Highly Efficient Photocatalytic Water Splitting

Abstract

The development of earth‐abundant, economical, and efficient photocatalysts to boost water splitting is a key challenge for the practical large‐scale application of hydrogen energy. In this study, g‐C3N4 loaded with different tungsten compounds (W2C, WS2, and W2N) is found to exhibit enhanced photocatalytic activities. W2C/g‐C3N4 displays the highest activity for the photocatalytic reaction with a H2 evolution rate of up to 98 μmol h−1, as well as remarkable recycling stability. The excellent photocatalytic activity of W2C/g‐C4N3 is attributed to the suitable band alignment in W2C/g‐C4N3 and high HER activity of the W2C cocatalyst, which promotes the separation and transfer of carriers and hydrogen evolution at the surface. These findings demonstrate that the tungsten carbide cocatalyst is more active for the photocatalytic reaction than the sulfide or nitride, paving a way for the design of novel and efficient carbides as cocatalysts for photocatalysis.

Bis‐Tridentate‐Cyclometalated Ruthenium Complexes with Extended Anchoring Ligand and Their Performance in Dye‐Sensitized Solar Cells.

“…Ruthenium sensitizers with NCN (derivatives of 1,3‐di(pyridine‐2‐yl)benzene) and NNC (derivative of 6‐phenyl‐2,2’‐bipyridine) type of tridentate cyclometalated ligands are known ,. In this work, we chose the former type, as they are easier to synthesize than the latter.…”

“…Ruthenium sensitizers with NCN (derivatives of 1,3-di(pyridine-2-yl)benzene) and NNC (derivative of 6-phenyl-2,2'-bipyridine) type of tridentate cyclometalated ligands are known. [23,24] In this work, we chose the former type, as they are easier to synthesize than the latter. Although, due to lowered symmetry, NNC ligated complexes possess more absorption bands than NCN ligated complexes, no clear work showed their better performance in solar cells.…”

Photon Upconversion Kinetic Nanosystems and Their Optical Response

“…[49,54,55] Benefiting from ample energy levels of the lanthanide ions, many excitation wavelengths that can produce efficient upconversion luminescence have been identified for different systems, e.g., ∼980 nm for Yb 3+ sensitized systems, [58] ∼808 nm for Nd 3+ sensitized systems, [95][96][97] and ∼808 nm and ∼1500 nm for Er 3+ solely doped nanoparticles. [98][99][100] Interestingly, with adequate assistance of interionic energy transfer, the above mentioned excitation-wavelength selection rule for efficient upconversion luminescence can be broken, as in the cases of energy-looping and photon avalanche induced upconversion processes. [101] In such circumstances, the excitation wavelength is allowed to be only resonant with excited state absorption transitions but not the ground state absorption.…”

“…In this situation, the very short pulse duration with the often associated high repetition rate (usually in the order of MHz) behaves equivalently to CW excitation when exciting UCNPs. [99] The key factor for the pumping of UCNPs is the temporal accumulation of incident photon flux, to some extent corresponding to the average excitation intensity rather than to the peak excitation intensity. [182] Actually, operation of an upconversion kinetic system at a transient state generally leads to the loss of efficiency, compared to CW excitation with identical excitation intensity, as indicated by numerical simulation performed by us.…”

Constructing 0D FeP Nanodots/2D g‐C3N4 Nanosheets Heterojunction for Highly Improved Photocatalytic Hydrogen Evolution

“…For the effective solar‐to‐fuel conversion, besides the main semiconductor photocatalyst, a noble‐metal‐based co‐catalyst is generally required to construct heterojunction systems with optimized electron transfer pathway for the accelerated charge transport and boosted HER efficiency. Over the past few years, numerous earth‐abundant, noble‐metal‐free compounds have been explored as ideal HER co‐catalysts for the construction of 2D g‐C 3 N 4 ‐based heterojunction photocatalysts . Among them, transition metal phosphides, such as Ni 2 P, CoP and MoP, have been widely employed as a suitable alternative to the noble‐metal‐based co‐catalysts.…”