Quantifying and Comparing Fundamental Loss Mechanisms to Enable Solar‐to‐Hydrogen Conversion Efficiencies above 20% Using Perovskite–Silicon Tandem Absorbers

Self Cite

While direct solar‐driven water splitting has been investigated as an important technology for low‐cost hydrogen production, the systems demonstrated so far either required expensive materials or presented low solar‐to‐hydrogen (STH) conversion efficiencies, both of which increase the levelized cost of hydrogen (LCOH). Here, a low‐cost material system is demonstrated, consisting of perovskite/Si tandem semiconductors and Ni‐based earth‐abundant catalysts for direct solar hydrogen generation. NiMo‐based hydrogen evolution reaction catalyst is reported, which has innovative “flower‐stem” morphology with enhanced reaction sites and presents very low reaction overpotential of 6 mV at 10 mA cm−2. A perovskite solar cell with an unprecedented high open circuit voltage (Voc) of 1.271 V is developed, which is enabled by an optimized perovskite composition and an improved surface passivation. When the NiMo hydrogen evolution catalyst is wire‐connected with an optimally designed NiFe‐based oxygen evolution catalyst and a high‐performance perovskite‐Si tandem cell, the resulting integrated water splitting cell achieves a record 20% STH efficiency. Detailed analysis of the integrated system reveals that STH efficiencies of 25% can be achieved with realistic improvements in the perovskite cell and an LCOH below ≈$3 kg−1 is feasible.

Section: Resultsmentioning

confidence: 99%

Direct Solar Hydrogen Generation at 20% Efficiency Using Low‐Cost Materials

Wang

Sharma

Arandiyan

et al. 2021

Self Cite

“…To assess the potential enhancements in STH efficiency, theoretical modeling based on previously established methods [37,38] was employed to evaluate the current system. The triple-junction cell was modeled under 1 sun AM1.5G illumination using the transcendental solar cell equation, with realistic losses introduced via loss parameters fitted to experimental data.…”

Section: Computational Analysismentioning

confidence: 99%

Unlocking Ultra‐High Performance in Immersed Solar Water Splitting with Optimised Energetics

Butson,

Sharma,

Tournet

et al. 2023

Self Cite

This research introduces a pioneering approach to solar water splitting technology, utilizing an innovative, highly efficient immersed system. The system incorporates a flexible array of electrochemical and photoelectrochemical cells, powered by high‐performance III‐V triple‐junction cells. Remarkably, this method significantly boosts the solar‐to‐hydrogen (STH) conversion efficiency, reaching a record 20.7% under 1 sun illumination, employing earth‐abundant catalysts operating at ambient temperature. These findings highlight extensive scope for further optimization, including minimizing optical transmission losses, mitigating shading effects, and reducing the overpotential of the electrochemical cells, thereby augmenting the STH efficiency to an estimated 28%. Through a comprehensive techno‐economic analysis, a levelized cost of hydrogen (LCOH) of 8.3 USD kg−1 is estimated, forecasting the potential for a reduction to a competitive 1.8 USD kg−1 with improved efficiency, increased capacity factors, and decreased production costs. A sensitivity analysis emphasizes the significant influence of factors such as III‐V cell cost, electrolyzer membrane cost and capacity factor on the LCOH. Overall, this study signifies crucial progress toward a highly efficient and economically viable solar water splitting solution, promising a sustainable route for hydrogen production.

“…STH efficiencies were modeled using previously established methods. [55,56] Ideal STH efficiencies (blue) were calculated using the detailed balance approach, while realistic STH efficiencies (green) were calculated using the best reported solar cell performances for given semiconductor systems (Table S7, Supporting Information) combined with the cocatalyst foils developed in this work. Realistic solar cells were modeled under 1 Sun AM1.5G illumination using the transcendental solar cell equation, with realistic losses introduced via loss parameters fitted to experimental data.…”

Section: The Future Potential Of Cocatalyst Foilsmentioning

confidence: 99%

Surface‐Structured Cocatalyst Foils Unraveling a Pathway to High‐Performance Solar Water Splitting

Butson

Sharma

Chen

et al. 2021

Self Cite

and photovoltaic-electrochemical (PV-EC) [11][12][13] water splitting have reignited interest in the prospect of a sustainable hydrogen economy, with several efficiency records being broken in quick succession. Immersed photoelectrodes and PEC systems have long been a tantalizing goal, simultaneously offering the advantages of both PC and PV-EC systems while avoiding many of their respective drawbacks. First, photoelectrodes are compact, lowering material usage and electrical losses. This also minimizes the distance that photogenerated charge carriers must travel to reach the electrolyte, reducing the ohmic losses associated with carrier collection and subsequent redistribution across the catalytic surface. Second, H 2 and O 2 are evolved at opposite electrodes and can therefore be collected separately. Third, photoelectrodes do not require additional thermal management, as the electrolyte itself can act as a coolant. [14] This becomes particularly useful when operating under concentrated light. Despite recent breakthroughs, the stabilization of highefficiency photoelectrodes remains a key issue; no previously reported immersed system has maintained a solar-to-hydrogen (STH) efficiency of over 10% for longer than 5 days. [9] Instability is often encountered due to the fact that many proven An ideal catalytic interface for photoelectrodes that enables high efficiency and long-term stability remains one of the keys to unlocking high-performance solar water splitting. Here, fully decoupled catalytic interfaces realized using surfacestructured cocatalyst foils are demonstrated, allowing optimized photoabsorbers to be combined with high-performance earth-abundant cocatalysts. Since many earth-abundant cocatalysts are deposited via solution-based methods, deposition on chemical-sensitive photoabsorbers is a significant challenge. By synthesizing cocatalyst foils prior to device fabrication, photoabsorbers are completely isolated from corrosive chemical environments and are provided with outstanding protection during operation. Si and GaAs photoelectrodes prepared using Ni-based cocatalyst foils achieve excellent half-cell efficiencies and generate stable photocurrents for over 5 days. Furthermore, a GaAs artificial leaf achieves a solar-to-hydrogen efficiency of 13.6% and maintains an efficiency of over 10% for longer than nine days, an accomplishment that has not been previously reported for an immersed solar water splitting system. These results, together with theoretical calculations of other photoelectrode systems, demonstrate that cocatalyst foils offer a very attractive method for fabricating high-performance solar water splitting systems.