Prof. Julio Lloret-Fillol

The research lines since Prof. Lloret-Fillol has started the research group at the ICIQ are:

High Valent State Metals and Water Oxidation Catalysis (WOC)

Water is the most appealing global-scale source of electrons that can be used to store energy into chemical bonds. However, our understanding is limited (CCR 2017, 334, 2; AOC 2019, 71, 1; AIC 2019, 74, 151).

(a) We discovered highly efficient homogeneous Fe WO catalysts (Nat. Chem. 2011, 807), extended the reactivity to organic oxidations (CEJ 2012, 18, 13269) and predicted an exotic {Fe-O-Ce} intermediate (CEJ 2013, 19, 8042, ACIE-Highlighted and Frontispiece). Later, we characterized the {Fe-O-Ce} intermediate (Nat.Commun. 2015 NCOMMS-14-03271A). Our mechanistic studies (CEJ 2014, 20, 5696 and Inorg. Chem 2014, 53, 5474) and characterization of high valent Fe(V)-oxo and -nitrido systems (JACS 2017, 139, 9168, JACS 2018, 140, 3916) led us to design highly active homogenous WOC by deuteration of oxidation-sensitive sites (JACS 2019, 141, 323) showing the molecularity together with electrochemical studies (ACS Cat 2021, 11, 2583). We elucidated the WO mechanism of equivalent Ru complexes (CEJ 2016, 22, 20111, Nat. Chem. 2021 13, 800, ChemElectroChem 2021, 8, 10.1002/celc.202101271, Cover).

(b) To find highly efficient OER, we Initially explored imidazolate-based Co-Metal-Organic Frameworks (MOFs), demonstrating that they displayed low overpotentials (319 mV at 10 mA·cm-2) for Oxygen Evolution Reaction (OER) and extraordinarily stability even when used as a catalyst for overall water splitting (both OER and HER) without any sign of fatigue after > 120 h. Interestingly, the MOF was converted fast to a more active Co(O)OH phase during electrocatalytic oxygen evolution. (ACS Appl. Energy Mater. 2019, 2, 8930). Then, we searched directly for doped metal oxides since they are highly efficient and robust OER catalysts. We developed NiM’Ox (M = Fe, Co, Mn, Zn) mixed metal oxides by solution combustion that produced among the best catalytic systems described in the literature (< 190 mV at 10 mA·cm-2 at pH 13, J. Mater. Chem. A, 2021, 9, 12700) and served as a model to understand the OER (J. Am. Chem. Soc. 2022, 144, 7622). This in-situ catalyst growing (ICG) method to fabricate self-supported OER catalytic electrodes was also patent-protected since it provides a single, fast, and low-temperature fabrication step that facilitates automatisation at reduced costs. Notably, the in-situ catalyst growing (ICG) technology for the specific application of electrodes for Alkaline Hydrogen Production Electrolyzers is under development by the Spin-Off JOLTECH SOLUTIONS (JOLT).

Reductive chemistry for the synthesis of fine chemicals and fuels

Prof. Lloret-Fillol was awarded as a Consolidator Grant of the European Research Council to develop this project.

(a) We developed modular HER active Co complexes under photo- and electrochemical conditions (>8500 TON, 52000 TON/h) (ChemSci 2018, 9, 2609; Editors’ Choice, ACS Cat 2019, 9, 5837).

(b) We elucidated the CO2-to-CO mechanism for the same cobalt complexes (JACS 2020, 142, 120), developed NHCs Mn electrocatalyst for CO2-to-CO reduction, with a TOF of 3·105 s-1 (ACIE 2018, 57, 4603) and the first electroactive COFs based on {Mn(CO)3} (ACS Cat 2021, 11, 7210, Cover) and Fe complexes (ACS Cat 2021 11, 615 & 11, 15212).

(c) Beyond Artificial Photosynthesis: We hypothesised that by using catalysts previously developed for HER and CO2RR in combination with the reductive enough photosensitisers, we could catalyse other reducing transformations using water as a source of H2 and light as the driving source. For instance, the system presents an unprecedented selectivity for reducing acetophenone versus aliphatic aldehydes (ChemSci 2017, 8, 4739, Cover picture & highlighted in chemistry world & chemistry views and ChemComm 2018, 9643). The same catalytic system can reduce olefins (ChemSci 2022, 13, 4270). We also found that developed catalysts activate challenging inert chloroalkanes under mild conditions yielding cross-coupling transformations (Angew Chem Int Ed 2019, 58, 1869; and Angew Chem Int Ed 2022, 61, e202114365, Cover).

Catalysis with Reticular Materials. Reticular Materials for Catalysis

Site isolation of unstable catalytic species within a reticular material is an appealing strategy for mitigating catalyst decomposition while creating catalysts with improved activity and robustness. In this regard, we found that this strategy works for COFs. For instance, we developed the first 2D-COF electroactive based on {Mn(CO)3}, showing higher catalytic activity and low overpotential (c.a. 300 mV) in water at pH 7.5 for the synthesis of syngas than its molecular counterpart. Moreover, by a homemade ATR-IR-Spectroelectrochemical cell, we studied the mechanism, proposing that the mechanical constraint of the COF avoids the deleterious formation of the Mn-Mn dimer (ACS Catal 2021, cover picture). As a result, current densities for CO2-to-CO improve in flow cells (75 mA·cm-2, Fig 2). Moreover, we have also developed a 2D-COF based on single cobalt sites coordinated (COFbpyCo) exploiting the isolated nature of the cobalt sites to stabilise low-valent single sites and catalyse the hydroboration of olefins. Indeed, the COF shows excellent reactivity while the corresponding molecular complex is inactive. Experimental and computational studies suggested the {(bpy•–)CoI(THF)2} moiety as the active catalytic species within the COF. The mechanism follows oxidative boryl migration, isomerisation, and reductive elimination to form the boronate ester (ACS Catal. 2023, 13, 3044).

Robotization, AI and scientific equipment

We aim to accelerate catalyst discovery through high throughput techniques and an advanced robotic platform. We actively work on the development of new photoreactors and electrochemical cells to speed up the study of chemical reactivity. In particular, we have developed photoreactors with different footprints where we can control the temperature and light intensity of the reactions, allowing us to accelerate research in photocatalysis. On the other hand, we are developing automating lab processes by incorporating high-throughput screening (HTS), autonomous labs, and digitalization techniques for electrocatalysis. This approach targets the development of electrocatalysts, crucial for processes such as water splitting to produce hydrogen and transforming CO₂ into sustainable fuels.

Technology transference

From the research of the group, 2 spin-offs has been created: Treellum technologies (J.L.-F. CSO and co-founder, http://treellumtechnologies.com/) and Jolt technologies (J.L.-F. CS and o-founder, https://jolt-solutions.com/”), In Treellum we aim to develop the most advances photoreactors to advance photo-catalysis, where in JOLT we exploit our patented technology for manufacturing electrodes for Alkaline Electrolyzes for H2 production.