skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Scalable, highly stable Si-based metal-insulator-semiconductor photoanodes for water oxidation fabricated using thin-film reactions and electrodeposition
Title: Scalable, highly stable Si-based metal-insulator-semiconductor photoanodes for water oxidation fabricated using thin-film reactions and electrodeposition
Abstract Metal-insulator-semiconductor (MIS) structures are widely used in Si-based solar water-splitting photoelectrodes to protect the Si layer from corrosion. Typically, there is a tradeoff between efficiency and stability when optimizing insulator thickness. Moreover, lithographic patterning is often required for fabricating MIS photoelectrodes. In this study, we demonstrate improved Si-based MIS photoanodes with thick insulating layers fabricated using thin-film reactions to create localized conduction paths through the insulator and electrodeposition to form metal catalyst islands. These fabrication approaches are low-cost and highly scalable, and yield MIS photoanodes with low onset potential, high saturation current density, and excellent stability. By combining this approach with a p+n-Si buried junction, further improved oxygen evolution reaction (OER) performance is achieved with an onset potential of 0.7 V versus reversible hydrogen electrode (RHE) and saturation current density of 32 mA/cm2under simulated AM1.5G illumination. Moreover, in stability testing in 1 M KOH aqueous solution, a constant photocurrent density of ~22 mA/cm2is maintained at 1.3 V versus RHE for 7 days.  more » « less
Award ID(s):
1702944 1720595
PAR ID:
10252588
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Nature Publishing Group
Date Published:
Journal Name:
Nature Communications
Volume:
12
Issue:
1
ISSN:
2041-1723
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; ; ; ; (, Nanoscale)
    null (Ed.)
    Oxygen evolution reaction (OER) catalysts are critical components of photoanodes for photoelectrochemical (PEC) water oxidation. Herein, nanostructured metal boride MB (M = Co, Fe) electrocatalysts, which have been synthesized by a Sn/SnCl 2 redox assisted solid-state method, were integrated with WO 3 thin films to build heterojunction photoanodes. As-obtained MB modified WO 3 photoanodes exhibit enhanced charge carrier transport, amended separation of photogenerated electrons and holes, prolonged hole lifetime and increased charge carrier density. Surface modification of CoB and FeB significantly enhances the photocurrent density of WO 3 photoanodes from 0.53 to 0.83 and 0.85 mA cm −2 , respectively, in transient chronoamperometry (CA) at 1.23 V vs. RHE (V RHE ) under interrupted illumination in 0.1 M Na 2 SO 4 electrolyte (pH 7), corresponding to an increase of 1.6 relative to pristine WO 3 . In contrast, the pristine MB thin film electrodes do not produce noticeable photocurrent during water oxidation. The metal boride catalysts transform in situ to a core–shell structure with a metal boride core and a metal oxide (MO, M = Co, Fe) surface layer. When coupled to WO 3 thin films, the CoB@CoO x nanostructures exhibit a higher catalytic enhancement than corresponding pure cobalt borate (Co-B i ) and cobalt hydroxide (Co(OH) x ) electrocatalysts. Our results emphasize the role of the semiconductor–electrocatalyst interface for photoelectrodes and their high dependency on materials combination. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al (, Advanced Functional Materials)
    Abstract 1D materials, such as nanofibers or nanoribbons are considered as the future ultimate limit of downscaling for modern electrical and electrochemical devices. Here, for the first time, nanofibers of a solid solution transition metal trichalcogenide (TMTC), Nb1‐xTaxS3, are successfully synthesized with outstanding electrical, thermal, and electrochemical characteristics rivaling the performance of the‐state‐of‐the art materials for each application. This material shows nearly unchanged sheet resistance (≈740 Ω sq−1) versus bending cycles tested up to 90 cycles, stable sheet resistance in ambient conditions tested up to 60 days, remarkably high electrical breakdown current density of ≈30 MA cm−2, strong evidence of successive charge density wave transitions, and outstanding thermal stability up to ≈800 K. Additionally, this material demonstrates excellent activity and selectivity for CO2conversion to CO reaching ≈350 mA cm−2at −0.8 V versus RHE with a turnover frequency number of 25. It also exhibits an excellent performance in a high‐rate Li–air battery with the specific capacity of 3000 mAh g−1at a current density of 0.3 mA cm−2. This study uncovers the multifunctionality in 1D TMTC alloys for a wide range of applications and opens a new direction for the design of the next generation low‐dimensional materials. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; ; et al (, Angewandte Chemie International Edition)
    Abstract Aldehyde‐assisted water electrolysis offers an attractive pathway for energy‐saving bipolar hydrogen production with combined faradaic efficiency (FE) of 200% while converting formaldehyde into value‐added formate. Herein we report the design and synthesis of noble metal‐free Cu6Sn5alloy as a highly effective electrocatalyst for formaldehyde electro‐oxidative dehydrogenation, demonstrating a geometric current density of 915 ± 46 mA cm−2at 0.4 V versus reversible hydrogen electrode, outperforming many noble metal electrocatalysts reported previously. The formaldehyde‐assisted water electrolyzer delivers 100 mA cm−2at a low cell voltage of 0.124 V, and a current density of 486 ± 20 mA cm−2at a cell voltage of 0.6 V without any iR compensation and exhibits nearly 200% faradaic efficiency for bipolar hydrogen production at 100 mA cm−2in 88 h long‐term operation. Density functional theory calculations further confirm the notably lowered barriers for dehydrogenation and Tafel steps on the Cu₆Sn₅ surface compared to Cu, underscoring its potential as a highly active catalyst. 
    more » « less
  4. ; ; ; ; ; ; ; ; ; ; et al (, Advanced Materials)
    Abstract Metal–organic frameworks (MOFs) are promising materials for electrocatalysis; however, lack of electrical conductivity in the majority of existing MOFs limits their effective utilization in the field. Herein, an excellent catalytic activity of a 2D copper (Cu)‐based conductive MOF, copper tetrahydroxyquinone (CuTHQ), is reported for aqueous CO2reduction reaction (CO2RR) at low overpotentials. It is revealed that CuTHQ nanoflakes (NFs) with an average lateral size of 140 nm exhibit a negligible overpotential of 16 mV for the activation of this reaction, a high current density of ≈173 mA cm−2at −0.45 V versus RHE, an average Faradaic efficiency (F.E.) of ≈91% toward CO production, and a remarkable turnover frequency as high as ≈20.82 s−1. In the low overpotential range, the obtained CO formation current density is more than 35 and 25 times higher compared to state‐of‐the‐art MOF and MOF‐derived catalysts, respectively. The operando Cu K‐edge X‐ray absorption near edge spectroscopy and density functional theory calculations reveal the existence of reduced Cu (Cu+) during CO2RR which reversibly returns to Cu2+after the reaction. The outstanding CO2catalytic functionality of conductive MOFs (c‐MOFs) can open a way toward high‐energy‐density electrochemical systems. 
    more » « less
  5. ; ; ; ; ; ; ; ; (, ENERGY & ENVIRONMENTAL MATERIALS)
    Regulating the selectivity toward a target hydrocarbon product is still the focus of CO2electroreduction. Here, we discover that the original surface Cu species in Cu gas‐diffusion electrodes plays a more important role than the surface roughness, local pH, and facet in governing the selectivity toward C1or C2hydrocarbons. The selectivity toward C2H4progressively increases, while CH4decreases steadily upon lowering the Cu oxidation species fraction. At a relatively low electrodeposition voltage of 1.5 V, the Cu gas‐diffusion electrode with the highest Cuδ+/Cu0ratio favors the pathways of hydrogenation to form CH4with maximum Faradaic efficiency of 65.4% and partial current density of 228 mA cm−2at −0.83 V vs RHE. At 2.0 V, the Cu gas‐diffusion electrode with the lowest Cuδ+/Cu0ratio prefers C–C coupling to form C2+products with Faradaic efficiency topping 80.1% at −0.75 V vs RHE, where the Faradaic efficiency of C2H4accounts for 46.4% and the partial current density of C2H4achieves 279 mA cm−2. This work demonstrates that the selectivity from CH4to C2H4is switchable by tuning surface Cu species composition of Cu gas‐diffusion electrodes. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email