Effect of particle size of La₅Ti₂CuS₅O₇on photoelectrochemical properties in solar hydrogen evolution

Abstract

La 5 Ti 2 CuS 5 O 7 (LTC) is an oxysulphide semiconductor with spatially separated one-dimensional carrier transport properties that are applicable to sunlight-driven photoelectrochemical (PEC) water splitting. In this study, rod-like LTC particles with different sizes were prepared by controlling the annealing duration and sequential centrifugation conditions, and their PEC properties were investigated to develop a material design strategy tailored for hydrogen evolution. The larger LTC particles were found to generate a higher photocurrent. The hypothetical half-cell solar-to-hydrogen energy conversion efficiency of Mg-doped LTC reached 0.17% at 0.6 V vs. RHE. The faradic efficiency of the PEC hydrogen evolution was also confirmed to exceed 90%. Scanning electron microscopy images of PEC-deposited Pt nanoparticles showed that they were selectively loaded on the edge surface of large LTC particles, while they were loaded on both the lateral and edge surfaces of small LTC particles. This is presumably because the large LTC particles contained lower densities of defects and grain boundaries, interrupting the spatially separated carrier transport. Therefore, the use of well-grown, rod-like LTC particles is concluded to be favourable for PEC hydrogen production.

Bismuth Silver Oxysulfide for Photoconversion Applications: Structural and Optoelectronic Properties

“…3-8 Recent efforts on the synthesis and characterization of suitable semiconductors led to the development of several material families, including oxynitrides, [9][10] oxysulfides [11][12] and carbonitrides, [12][13][14] for water splitting. Despite the efforts devoted to this research, the maximum photoconversion efficiency obtained experimentally is still far from the ideal one predicted by thermodynamics.…”

Effects of Calcination Temperature on the Physical Properties and Hydrogen Evolution Activities of La5Ti2Cu(S1‐xSex)5O7 Photocatalysts

“…Most likely, calcination below 1273 K was insufficient to reduce defects in LTCSO samples synthesized by solid‐state reactions. Our previous study suggested that the synthesis of LTCSO under milder conditions induces defects that prevent charge transfer . By contrast, the LTCSO calcined at 1323 K was accompanied by the generation of white impurities, which are thought to have affected the photocatalytic activity.…”

“…This material is applicable to photocatalytic and photoelectrochemical H 2 and O 2 evolution reactions with the aid of sacrificial reagents and an external power source, respectively . The photocurrent generated by a LTCSO photocathode can be improved by increasing the particle size up to several micrometers as a result of decreases in defect densities and the long‐range diffusion of carriers on the order of micrometers . La 5 Ti 2 Cu(S 1‐ x Se x ) 5 O 7 (LTCS 1‐ x Se x O) solid solutions can also be synthesized by solid‐state reactions .…”

Optimal Metal Oxide Deposition Conditions and Properties for the Enhancement of Hydrogen Evolution over Particulate La5Ti2Cu1−xAgxS5O7 Photocathodes

“…In addition, doped LTC 1− x A x photocathodes have been found to generate photocurrent at a remarkably positive potential of 0.9 V vs. RHE. Therefore, LTC 1− x A x is a promising photocathode material for unassisted sunlight‐driven water splitting based on p/n‐PEC cells …”