Efficient Indium Sulfide Photoelectrode with Crystal Phase and Morphology Control for High-Performance Photoelectrochemical Water Splitting

Abstract

Crystal phase control of materials plays an important role on their properties in photocatalysis and photoelectrocatalysis. Herein, cubic and tetragonal phase control of In2S3 photoanodes with various morphologies on indium tin oxide transparent conductive glass substrate have been successfully realized through a simple hydrothermal method for the first time. According to the detailed characterization analysis, we proposed a model to interpret the phase transition of In2S3 along with hydrothermal reaction time. The photoelectrochemical tests suggest that the cubic phase In2S3 nanocubes with cuneiform morphology exhibit a photocurrent density of 0.50 mA/cm2 at 1.23 V vs RHE benefit by the special structure for efficient charge separation and transfer. This is the highest photocurrent values of single In2S3 crystals best to our knowledge. Furthermore, the photoelectrochemical performance of In2S3 can be greatly improved by depositing a Co–Pi cocatalysts layer. The composites show a 1.36-fold increase of photocurrent density (0.68 mA/cm2 at 1.23 V vs RHE) compared to that of pristine In2S3. This work highlights that In2S3 can be an attractive candidate as photoanodes for photoelectrochemical water splitting, and the crystal phase control presents a new avenues to the exploration and design of photoelectrodes for realizing superior performances.

β-In2S3 as Water Splitting Photoanodes: Promise and Challenges

“…The phase and morphology of pristine In 2 S 3 was controlled with different hydrothermal reaction time [75]. Hydrothermal method enables the formation of high quality of the ohmic contact between the resultant film and the substrate which makes it suitable for the preparation of photoanodes.…”

“…Among the various metal sulfides, β-In 2 S 3 is regarded as a potential candidate recently in photocatalytic applications due to the less environmental and health concerns, high photoelectric sensitivity, moderate charge transport, and high photoconductivity as briefly mentioned above [37,75,82]. Already in the field of solar cells, In 2 S 3 received a great attention as an alternative to the cadmium sulfide (CdS) buffer layer which contains harmful element, cadmium (Cd), in the material [54].…”

“…Since the position of conduction band edge is relatively negative, it is feasible to construct type II heterostructures with various materials as depicted in the inset of Fig. 3a [75]. Furthermore, its band gap can be adjusted through the quantum confinement effect owing to the large exciton Bohr diameter of 33.8 nm [35].…”

“…There are some reports that β-In 2 S 3 with cubic structure is beneficial for photocatalytic reaction because of the disordered indium vacancies [65,75]. Fu et al proposed that sulfur-bridged indium ions in In 2 S 3 crystal structure offer as charge transport pathways of charge carriers to move from the interior of the material to the surface [65].…”

Important Phase Control of Indium Sulfide Nanomaterials by Choice of Indium(III) Xanthate Precursor and Thermolysis Temperature

“…2 eV . The notable recent advances on the specialised applications of indium sulfide include fabrication of photoanodes for photoelectrochemical water splitting, nanohybrid paper electrodes for Na‐ion batteries, as well as a thorough investigation of charge transport behaviour of indium sulfide under high pressures . These applications have in common the necessity to utilize indium sulfide in its pure phases.…”