High-performance, bias-free solar valorization of nitrate and iodide to ammonia and triiodide in acidic media
Journal
Applied Catalysis B: Environmental
Journal Volume
399
Start Page
127131
ISSN
09263373
Date Issued
2026-12-15
Author(s)
Liu, Tsung-Hsin
Thanajantaporn, Nutthun
Huang, Yung-Hung
Lin, Jou-Chun
Lee, Lo-Yu
Yu, Cheng-Yu
Tang, Ya-Wen
Ho, Ya-Lun
Shiue, Jessie
Wang, Di-Yan
Abstract
The sustainable synthesis of ammonia (NH3) under ambient conditions remains a grand challenge in catalysis and energy science. Here, we present a high-performance, fully bias-free photoelectrochemical (PEC) platform that couples nitrate reduction reaction (NtRR) with iodide oxidation reaction (IOR) using graphene-passivated silicon heterojunction (Gr/SiHJT) photoelectrodes. By integrating Cu-decorated Gr/SiHJT photocathode with graphene-catalyzed IOR photoanode, the system delivers a large photovoltage, rapid interfacial charge transfer, and exceptional chemical stability under strongly acidic conditions. The Cu/Gr/SiHJT photocathode achieves a high Faradaic efficiency (FE) of 98.6% with an NH₃ yield rate of 148.5 µmol h−1 cm−2 at 0.26 V vs RHE, while the Gr/SiHJT photoanode catalyzes IOR with near-unity selectivity. In a fully bias-free artificial-leaf configuration under one-sun illumination (AM 1.5 G, 100 mW cm−2), the paired photoelectrodes simultaneously produce NH₃ and triiodide (I₃⁻) at yield rates of 65.0 and 285.1 µmol h−1 cm−2, respectively, and maintain stable operation for over 120 h. This work establishes a unified materials–architecture strategy that integrates graphene protection, SiHJT light harvesting, and selective nitrate (NO3-)/iodide (I-) catalysis, enabling fully solar-driven NO3- valorization.
Subjects
Bias-free system
Photoelectrochemical nitrate reduction reaction
Solar-to-ammonia conversion
Valuable chemical conversion
Publisher
Elsevier B.V.
Type
journal article