Major research themes/interests

      Dr Cubillas research career can be framed in the broad field of mineral crystal-solution interface geochemistry and the application of advanced scanning probe microscopy. This field is of great importance in many areas critical to human well-being including heavy-metal remediation, radioactive-waste encapsulation/disposal, diagenesis, CO2 sequestration, organic pollutant transport, soil development in addition to many other disciplines in the Earth Sciences. Within this subject Dr Cubillas is particularly interested in the study of:

• Understanding the fundamental aspects that control the interactions between ions or organic molecules and mineral surfaces.
• Nucleation and growth mechanisms of minerals and related nanoporous materials.
• Dissolution rates of minerals and how they are influenced by the presence of different ions and organic species.
• Precipitation of secondary minerals in coupled dissolution/precipitation systems.
• Role of surface covering on coupled dissolution/precipitation systems.
• Heavy metal pollution and the application of minerals for environmental remediation.
• Measurement of mineral’s surface properties at the nanoscale, including wettability, stiffness and friction.
• Scanning probe microscopy development.

Academic biography

     From 2013 to 2019 Dr Cubillas was a lecturer of Geochemistry at the Earth Sciences Department, Durham University. During this time, the main research lines on which he was involved were: understanding clay mineral-organic interactions in conditions relevant for Enhanced Oil Recovery (in collaboration with Prof. Chris Greenwell and BP); understanding the nanomechanical properties of shales (in collaboration with Prof Andy Aplin and Shell); mineral dissolution and precipitation reactions (in collaboration with Dr Amalia Jimenez from the University of Oviedo, Spain); interaction or organic compounds and anions with layered double hydroxide (in collaboration with Prof. Chris Greenwell and SCG); use of zeolites in the production of biofuels and their use as soil amendments (in collaboration with Dr David de Haro from the Universidad Autonoma the Nuevo Leon, Mexico); nanomechanical characterisation of cells (Dr Karakesisoglou). Finally, Dr Cubillas designed and built a second-generation hydrothermal atomic force microscopy (under a NERC Proof of concept grant).   

     From 2006 to 2013 Dr Cubillas worked hold two postdoctoral positions at the Centre for Nanoporous Materials, The University of Manchester, under the supervision of Prof. Michael W. Anderson and Dr Martin Attfield. During this time his research concentrated mainly on understanding the fundamental mechanisms of the crystal growth of zeolites, zeotypes and metal organic frameworks materials (MOF) through ex-situ and in-situ scanning probe microscopy. Some of this work was carried out with academic collaborators from across the world (Stockholm, Versailles, Norway, Bath, UCL, Utrecht) and industry (Exxon-Mobil, Sintef). The most important results during this time were: a ground-breaking study on the energetics of zeolite L dissolution; the first-ever in-situ SPM study of a microporous material (zincophosphate-sodalite); first-of-a-kind studies on the crystal growth mechanisms (and morphological control) of the industrially relevant materials: zeolite-A, STA-7, SAPO-34, MAPO-5 and Silicalite. With respect to his work studying MOFs, Dr Cubillas carried out the first ever in-situ study on the crystal growth of MOF-5. Results show that by changing the solution stoichiometry (Zn to linker ratio) a change in the relative growth rates of different steps and facets can be induced. This knowledge was successfully applied to modify the shape of MOF-5 crystals from a cubic to an octahedral morphology. This very important result provides, for the first time, with a post-synthesis modulator-free route to modify the shape of this important material. Furthermore, Dr Cubillas studied the effect of Co incorporation on MOF-5 during crystal growth from dilute solutions and demonstrated the ability of growing core-shell-shell MOF-5 crystals with varying Co/Zn ratios. In addition, Dr Cubillas research led to the discovery of a new ZIF-76 (benzimidazolate) material through the heteroepitaxial growth over ZIF-76., were the expensive 5-Chlorobenzimidazole linker was substituted for the cheaper benzimidazole. Finally, through his experimental work on crystal growth Dr Cubillas contributed to the validation of the Monte Carlo computer model CrystalGrower. Development of this computer model received the 2021 Stephanie L Kwolek Award, given by the Materials Chemistry Division of the Royal Society of Chemistry.

     From 2005 to 2006 Dr Cubillas hold a postdoctoral position at Wright State University, Dayton, OH, USA, under the supervision of Prof. Steven Higgins. His research focused on the application of friction force microscopy (FFM) to study of the growth of Cd-Ca and Sr-Ca carbonate solid-solutions over calcite. Results obtained provide new insight into the chemical evolution in heteroepitaxially grown minerals as well into the fundamental origin of friction forces in single asperity contacts. In Dr Cubillas aided in the development of the step tracking AFM originally conceived by Prof. Higgins.

     Dr Cubillas was awarded a PhD in Geochemistry from the University of Oviedo, Spain, in February 2005. His research focused on the study of the interactions between heavy metals and biogenic and abiogenic calcium carbonate. The most important results from his PhD were: the determination of an empirical relation to describe the dissolution rates of three different biogenic carbonates; quantifying the effect of metal carbonate coatings on the dissolution rate of the underlying carbonates; quantifying the removal rate and total cadmium uptake capacity of cadmium by biogenic and abiogenic carbonates under different chemical conditions and in the presence of other heavy metals (Pb, Zn, Cu and Co); establishing the precipitation/crystal growth mechanism of Cd-Ca carbonate solid solutions over calcite/aragonite under coupled dissolution-precipitation conditions. As part of his PhD, Dr Cubillas carried out two visits to the Laboratoire des Mécanismes et Transferts en Géolgie in Toulouse, France (under the supervision of Prof. Eric H. Oelkers) and one visit to the Institut für Mineralogie (under the supervision of Professor Andrew Putnis).

Research Projects & External Funding

2018 Global Impact Acceleration Account – Mexico (Co-I). Title closing the Loop on Sustainable Metal Mine Water Remediation in Emerging Economies. (£40000).

2018 Spanish government (Co-I). Title: Intercambio químico y evolución de texturas minerales asociados a reacciones de disolución-cristalización. (£1000000).

2016 BP summer studentship project (PI). Title: Understanding the role of temperature, solution stoichiometry and scale inhibitors on the growth of gypsum by means of scanning probe microscopy (£500).

2016 NERC Proof of concept grant (Co-I). Title: Fundamental Understanding of Oil Adhesion Under Reservoir Conditions (FOilCon). (£175000).

2015 Durham University Seedcorn fund grant (PI). Study of the interactions of pesticides with mineral phases by means of chemical force microscopy. (£4600).

2014 NERC Strategic capital grant (Co-I). Title: Scanning probe microscope – stable isotope mass spectrometer (SPM‐SIMS) for establishing mineral chemistry equibria. (£322296).

2014 2x BP summer studentship project (PI). Title: Understanding the nanoscale interactions of clays and sandstone surfaces: implications for enhanced oil recovery operations. (£1000).

2006 Austrian Government (Co-I). Title: Application of aragonite shells for the removal of aqueous metals from polluted soils and waste waters. (£130000).

PhD Supervision

2016 – 2019 Supervisor Dr. Nipada Santha. “Chemical force microscopy investigations related to Enhanced Oil Recovery”.

2013 - 2017 Co-supervisor of Dr. Rikan Kareen. “Enhanced oil recovery studies on Berea sandstone across multiple scales”.

2013-2016 Co-supervisor of Dr Thomas Undewood. “Molecular Dynamics Simulations of Clay-Oil-BrineInterfaces: Understanding Low-Salinity Enhanced Oil Recovery”.

2008-2012 Co-supervisor of Dr. Mark A. Holden. “Crystal Growth of Zincophosphates studied by In-Situ Atomic Force Microscopy”.