About

Shane Ardo is a faculty member at the University of California, Irvine, within the Department of Chemistry. His research interests encompass inorganic and organometallic physical chemistry, chemical physics, polymer science, materials, nanoscience, and related interdisciplinary fields. He is involved in exploring the fundamental aspects of these areas, contributing to the advancement of knowledge in physical chemistry and materials science. His work is situated within the UC Irvine School of Physical Sciences, where he engages in research and teaching to further understanding of complex chemical systems.

Research topics

• Computer Science
• Chemistry
• Materials science
• Nanotechnology
• Electrical engineering
• Engineering
• Systems engineering
• Optics
• Physics
• Condensed matter physics
• Environmental science
• Business
• Optoelectronics
• Library science
• Chemical physics
• Process engineering
• Environmental economics
• Photochemistry

Selected publications

• Thermally Assisted Photoelectrochemical Water Splitting with Rh-Doped SrTiO ₃ Nanoparticle Photocatalysts

  ACS Applied Nano Materials · 2026-05-21

  article

  Solar-based water splitting using suspensions of photocatalyst nanoparticles could be an attractive means for the production of hydrogen but requires ∼10% solar-to-hydrogen efficiency for economic viability. Here we investigate the effects of increasing temperature on the rate of photoelectrochemical (PEC) hydrogen evolution reaction (HER) for photocathodes based on visible light absorbing SrTiO3 nanoparticles doped with Rh (SrTiO3:Rh) and a p-Si/SiO2/Cr/Pt Schottky metal-insulator semiconductor (Si-MIS) diode. We construct our PEC cells using Aquivion, a perfluorosulfonic acid ionomer, which facilitates temperature control. Under visible light illumination, we observe that the HER rate for Si-MIS decreases by approximately 6× when temperature is increased from 25 °C to ∼40 °C, while the rate for SrTiO3:Rh increases by a factor of 2× over the same temperature range. We also observe that under UV (365 nm) illumination the PEC rates for the SrTiO3:Rh nanoparticle photocathodes increase by ∼10×. The increase in PEC efficiency is consistent with our previous report of improved photocarrier transport in SrTiO3:Rh nanoparticles with increasing temperature, and points to the significance of using heat both as a tool for gaining mechanistic insights into the water splitting process and to improve its efficiency.

  PublisherDOI

• A fresh perspective on the role of band bending, and related contributors, in light-driven production of electricity and chemicals

  Energy & Environmental Science · 2026-01-01 · 1 citations

  articleSenior authorCorresponding

  Distributions of net charge, and associated electric fields and potentials, for an equilibrated semiconductor pn-homojunction are identical to those of initial nonequilibrium flux and transport rate for each charged species, if light absorption is uniform in space.

  PublisherDOI

• A nanoporous capacitive electrochemical ratchet for continuous ion separations

  Nature Materials · 2026-03-13 · 1 citations

  articleCorresponding
  PublisherDOI

• Levelized cost and carbon intensity of solar hydrogen production <i>via</i> water splitting using a scalable and intrinsically safe photocatalytic Z-scheme raceway system

  Energy & Environmental Science · 2025-01-01 · 13 citations

  articleOpen access

  Schematic of photocatalytic type 2 Z-scheme raceway design with hydrogen reactor cylinders floating on an oxygen reactor raceway pool. The raceway concept enables a scalable, low-cost, and low-carbon intensity method of hydrogen production.

  PublisherOA PDFDOI

• Ratchet-Based Ion Pumps for Selective Ion Separations

  ECS Meeting Abstracts · 2025-11-24

  article

  Even though highly selective ion pumps are found in the membrane of every living cell, artificial ion selective separation is a longstanding unmet challenge in science and engineering. The development of a membrane-based ion separation technology can drive a dramatic progress in a wide range of applications such as: water treatment, bio-medical devices, extraction of precious metals from sea water, chemical sensors, solar fuels and more. In this contribution we report on the experimental demonstration of ion pumps based on an electronic flashing ratchet mechanism and their theoretical ion sorting performance. Electronic flashing ratchets are devices that utilize a temporal modulation of a spatially asymmetric electric field to drive steady state current. Like peristaltic pumps, where the pump mechanism is not in direct contact with the pumped fluid, electronic ratchets induce a net current with no direct charge transport between the power source and the pumped charge carriers. Thus, electronic ratchets can be used to pump ions in steady state with no electrochemical reactions between the power source and the pumped ions resulting in an 'all-electric' ion pump. Ratchet-based ion pumps (RBIPs) were fabricated by coating the two surfaces of nano-porous alumina wafers with metal, thus forming nano-porous capacitor-like devices. The electric field within the nano-pores is modulated by oscillating the capacitor voltage. Thus, when immersed in a solution, ions within the pores experience a modulating electric field resulting in ratchet-based ion pumping. The RBIPs performance was studied for various input signals, geometries, and solutions. RBIPs were shown to drive ionic current densities of several uA/cm^2 even when opposed by an electrostatic force. A significant ratchet action was observed with input signal amplitudes as low as 0.1V thus demonstrating that RBIPs can drive an ionic current with no associated redox reactions. An important hallmark of ratchets is the ability to invert the direction of particle flow with a change in the input signal frequency. The stopping frequency, which is the frequency at which the particle flux changes its direction, is determined by the potential distribution and particles transport properties. As a result, for a given ratchet, there can be a frequency at which particles with the same charge, but different diffusion coefficients, are transported in opposite directions. This concept, that was never applied to ion separations, can enable the extraction of ions with extremely low relative concentrations if their diffusion coefficient is even slightly different from the diffusion coefficient of other ions in the solution. We show by simulation, that for the prevalent ions in water, ions with a relative diffusion coefficient difference as small as 1% can be driven to opposite directions with a velocity difference as high as 1.2 mm/s. Since the direction of ion transport is determined by the input signal frequency, the sorting properties can be tuned in real time providing a simple fit-to-purpose solution for a variety of ion separations applications. Figure 1

  PublisherDOI

• Models and Measurements Quantify Photon Recycling, Charge-Carrier Diffusion and Photon Scattering Contributions to Photoluminescence in InP Nanowire Arrays

  The Journal of Physical Chemistry C · 2025-04-19 · 1 citations

  article

  Nanowire arrays present many unique advantages for solar-to-chemical energy conversion. One possible advantage is that photon recycling between neighboring nanowires has the potential to increase solar energy conversion efficiencies. Here, we explore three underlying mechanisms of optical and electronic coupling between neighboring nanowires─incident photon scattering, photon recycling, and charge-carrier transport from the photoexcited nanowire to the neighboring nanowire via the underlying substrate─using single nanowire-level microscopy and spectroscopy measurements. We present a comprehensive analysis of light absorption and emission of a single nanowire at open circuit, and subsequent re-absorption and re-emission by a neighboring nanowire. We developed a novel correlated single nanowire microspectroscopy and widefield imaging methodology to spatially resolve photon communication pathways between neighboring nanowires and selectively image re-emitted and reflected photons. We developed unique multiphysics models to couple wave optics and semiconductor photophysics to especially isolate contributions from photon recycling and electronic transport to photon emission from neighboring nanowires. By systematically varying the morphologies of the nanowires modeled, we identified pathways to maximize photon recycling between neighboring nanowires. We concluded that the measured photoluminescence is more strongly influenced by the diffusion of charge carriers as compared to photon recycling in materials with moderate-to-large charge-carrier mobilities (>10 cm2 V–1 s–1), and that photon recycling dictates photoluminescence intensity only when the charge-carrier mobility is low (<1 cm2 V–1 s–1). The experimental and simulation platforms developed herein for photon management strategies can be leveraged by the semiconductor photocatalysis community to enhance solar-to-chemical conversion efficiencies in semiconductor nanowire arrays.

  PublisherDOI

• Imaging nanoscale photocarrier traps in solar water-splitting catalysts

  ArXiv.org · 2025-12-31

  articleOpen access

  Defects trap photocarriers and hinder solar water splitting. The nanoscale photocarrier transport, trapping, and recombination mechanisms are usually inferred from ensemble-averaged measurements and remain elusive. Because an individual high-performing nanoparticle photocatalyst may outperform the ensemble average, design rules that would otherwise enhance catalytic efficiency remain unclear. Here, we introduce photomodulated electron energy-loss spectroscopy (EELS) in an optically coupled scanning transmission electron microscope (STEM) to map photocarrier localization. Using rhodium-doped strontium titanate (SrTiO3:Rh) solar water-splitting nanoparticles, we directly image the carrier densities concentrated at oxygen-vacancy surface trap states. This is achieved by separating photothermal heating from photocarrier populations through experimental and computational analyses of low-loss spectra. Photomodulated STEM-EELS enables angstrom-scale imaging of defect-induced photocarrier traps and their impact on photocatalytic efficiency.

  PublisherOA PDF

• Synthesis of 4,5-Disubstituted <i>o</i> -Phenylenediamines: An Enabling Platform for Electrochemical Investigations of Interfacial Ion Transfer Reactions

  The Journal of Organic Chemistry · 2025-12-08 · 1 citations

  articleOpen accessCorresponding

  O-phenylenediamines have emerged as powerful synthons for the installation of molecularly well-defined active sites conjugated to graphitic carbon electrode surfaces. These graphite-conjugated actives sites can serve as rich platforms for the electrochemical investigation of interfacial ion transfer reactions at the molecular level. But widespread utilization of this platform is restricted by the limited synthetic access to o-phenylenediamines bearing an array of additional functional groups. Herein, we present three distinct and modular synthetic strategies to symmetric and asymmetric 4,5-o-phenylenediamines. We demonstrate the utility of 4,5-o-dinitrobenzenes as relatively stable precursors to this class of compounds, as well as a modular route to 4,5-o-phenylenediamines in as little as 2 steps from commercial starting materials. We then show, using cyclic voltammetry, that graphitic electrodes modified with molecules obtained from our syntheses exhibit expected electrochemical responses.

  PublisherDOI

• Revealing the Role of Individual Metal-Support Interactions in Hydrogen Production for Heterogeneous Photocatalysts via 4DSTEM Techniques

  Microscopy and Microanalysis · 2025-07-01

  article
  PublisherDOI

• Author response for "Levelized cost and carbon intensity of solar hydrogen production from water electrolysis using a scalable and intrinsically safe photocatalytic Z-scheme electrochemical raceway system"

  2025-04-26

  peer-review
  PublisherDOI

Recent grants

• CAS: Assessing the Applicability of Marcus Theory to Excited-state Proton Transfer and Protonic Photochemical Energy Conversion

  NSF · $350k · 2021–2024

• SusChEM: Understanding and controlling photoinduced self-exchange reactions across sensitized mesoporous thin films to drive multiple-electron-transfer catalysis

  NSF · $385k · 2016–2020

Frequent coauthors

• Daniel V. Esposito

  Columbia University

  60 shared

• Zejie Chen

  University of California, Irvine

  51 shared

• Xiaoqing Pan

  University of California, Irvine

  44 shared

• Tadashi Ogitsu

  43 shared

• Tuan Anh Pham

  Lawrence Livermore National Laboratory

  41 shared

• Mingjie Xu

  University of California, Irvine

  40 shared

• Katherine E. Hurst

  40 shared

• Marcos F. Calegari Andrade

  Lawrence Livermore National Laboratory

  39 shared

Education

• B.S., Chemistry

  University of California, Irvine

  2006

• M.S., Chemistry

  University of California, Irvine

  2008

• Ph.D., Chemistry

  University of California, Irvine

  2012