Photocorrosion-Resistant Sb2Se3 Photocathodes with Earth Abundant MoSx Hydrogen Evolution Catalyst

<p>The poor stability of high efficiency photoabsorber materials in aqueous media is one factor holding back the realization of photoelectrochemical (PEC) water splitting for large scale, practical solar fuels generation. Here, we demonstrate that highly efficient thin film Sb₂Se₃–fabricated by a simple, low temperature selenization of electrodeposited Sb–is intrinsically stable towards photocorrosion in strongly acidic media (1 M H₂SO₄). Coupling with a photoelectrodeposited MoS_x hydrogen evolution catalyst gives high photocurrents (5 mA cm^-2 at 0 V vs RHE) and high stability without protective layers (10 h with ~20% loss). A low temperature sulfurization of the Sb₂Se₃-MoS_x stack dramatically improved the onset potential, resulting in high photocurrent densities up to 16 mA cm^-2 at 0 V vs RHE. The simplicity with which these photocathodes are fabricated, combined with the high photocurrents and stability, make Sb₂Se₃ a strong candidate for scalable PEC cells.</p

Steric Effects on CO₂ Reduction with Substituted Mn(bpy)(CO)₃X‑Type Catalysts on Multiwalled Carbon Nanotubes Reveal Critical Mechanistic Details

A series of Mn(bpy-R)(CO)3Br (bpy-R = 4,4′-R-2,2′-bipyridine) complexes with systematic substituent variations (R = H, –Me, –Et, tBu, and –Ph) are immobilized on multiwalled carbon nanotubes (MWCNTs) and investigated as electrocatalysts for CO2 reduction to study substituent effects on heterogenized molecular electrocatalysis. The electrochemical response and catalytic activity of each heterogenized complex are characterized, unveiling clear trends across the series investigated. Mn(bpy-Ph)(CO)3Br/MWCNT exhibited the best catalytic performance, producing CO with a Faradaic efficiency of 72% and a current density (JCO) of 7.0 mA/cm2 at low overpotential (η = 0.65 V). Adding steric bulk to the bpy ligands is shown to restrict Mn0–Mn0 dimerization and cause a shift to two-electron reduction occurring at less negative potentials. The apparent quantity of electroactive catalyst scales inversely with steric bulk, where Mn(bpy-Ph)(CO)3Br exhibits no distinguishable Faradaic features in CV under normal conditions. These results indicate that catalytic performance is optimized by the confinement of electroactive species to the MWCNT interface

Steric Effects on CO₂ Reduction with Substituted Mn(bpy)(CO)₃X‑Type Catalysts on Multiwalled Carbon Nanotubes Reveal Critical Mechanistic Details

A series of Mn(bpy-R)(CO)3Br (bpy-R = 4,4′-R-2,2′-bipyridine) complexes with systematic substituent variations (R = H, –Me, –Et, tBu, and –Ph) are immobilized on multiwalled carbon nanotubes (MWCNTs) and investigated as electrocatalysts for CO2 reduction to study substituent effects on heterogenized molecular electrocatalysis. The electrochemical response and catalytic activity of each heterogenized complex are characterized, unveiling clear trends across the series investigated. Mn(bpy-Ph)(CO)3Br/MWCNT exhibited the best catalytic performance, producing CO with a Faradaic efficiency of 72% and a current density (JCO) of 7.0 mA/cm2 at low overpotential (η = 0.65 V). Adding steric bulk to the bpy ligands is shown to restrict Mn0–Mn0 dimerization and cause a shift to two-electron reduction occurring at less negative potentials. The apparent quantity of electroactive catalyst scales inversely with steric bulk, where Mn(bpy-Ph)(CO)3Br exhibits no distinguishable Faradaic features in CV under normal conditions. These results indicate that catalytic performance is optimized by the confinement of electroactive species to the MWCNT interface

Steric Effects on CO₂ Reduction with Substituted Mn(bpy)(CO)₃X‑Type Catalysts on Multiwalled Carbon Nanotubes Reveal Critical Mechanistic Details

A series of Mn(bpy-R)(CO)3Br (bpy-R = 4,4′-R-2,2′-bipyridine) complexes with systematic substituent variations (R = H, –Me, –Et, tBu, and –Ph) are immobilized on multiwalled carbon nanotubes (MWCNTs) and investigated as electrocatalysts for CO2 reduction to study substituent effects on heterogenized molecular electrocatalysis. The electrochemical response and catalytic activity of each heterogenized complex are characterized, unveiling clear trends across the series investigated. Mn(bpy-Ph)(CO)3Br/MWCNT exhibited the best catalytic performance, producing CO with a Faradaic efficiency of 72% and a current density (JCO) of 7.0 mA/cm2 at low overpotential (η = 0.65 V). Adding steric bulk to the bpy ligands is shown to restrict Mn0–Mn0 dimerization and cause a shift to two-electron reduction occurring at less negative potentials. The apparent quantity of electroactive catalyst scales inversely with steric bulk, where Mn(bpy-Ph)(CO)3Br exhibits no distinguishable Faradaic features in CV under normal conditions. These results indicate that catalytic performance is optimized by the confinement of electroactive species to the MWCNT interface

Iron Pyrite Thin Film Counter Electrodes for Dye-Sensitized Solar Cells: High Efficiency for Iodine and Cobalt Redox Electrolyte Cells

Iron pyrite has been the material of interest in the solar community due to its optical properties and abundance. However, the progress is marred due to the lack of control on the surface and intrinsic chemistry of pyrite. In this report, we show iron pyrite as an efficient counter electrode (CE) material alternative to the conventional Pt and poly(3,4-ethylenedioxythiophene (PEDOT) CEs in dye-sensitized solar cells (DSSCs). Pyrite film CEs prepared by spray pyrolysis are utilized in I₃^–/I^– and Co(III)/Co(II) electrolyte-mediated DSSCs. From cyclic voltammetry and impedance spectroscopy studies, the catalytic activity is found to be comparable with that of Pt and PEDOT in I₃^–/I^– and Co(III)/Co(II) electrolyte, respectively. With the I₃^–/I^– electrolyte, photoconversion efficiency is found to be 8.0% for the pyrite CE and 7.5% for Pt, whereas with Co(III)/Co(II) redox DSSCs, efficiency is found to be the same for both pyrite and PEDOT (6.3%). The excellent performance of the pyrite CE in both the systems makes it a distinctive choice among the various CE materials studied