In recent developments within green chemistry, researchers have explored biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More as a sustainable material for electrocatalysts. A study has demonstrated the synthesis of cobalt phosphide-loaded biochar (CoP@P-yeast) using a phosphorus-accumulating mutant strain of Saccharomyces cerevisiae. This innovative process offers a resource-efficient method for generating high-performance electrocatalysts suitable for hydrogen evolution reactions (HER) and nitrate reduction reactions (NO₃⁻RR).

The yeast strain (S. cerevisiae NOF-1) used in this study is notable for its capacity to accumulate up to 8.5% phosphorus within its cells, primarily as polyphosphate. This high phosphorus content is pivotal for the synthesis of transition metal phosphides (TMPs), materials valued for their electrocatalytic properties. Traditionally, TMP synthesis relies on hazardous chemical precursors, raising costs and environmental concerns. This bio-based approach circumvents these issues by using yeast biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More as a precursor, demonstrating environmental and economic advantages.

The researchers employed a two-step method: first, treating the yeast cells with tetrahydrofuran (THF) in a water-based cosolvent to enhance cobalt ion penetration, followed by pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More at 900°C under nitrogen gas. This procedure facilitated the formation of CoP, distinguishing it from previous methods that typically yielded Co₂P. Key to CoP formation was the yeast’s high phosphorus content, along with controlled pyrolysis conditionsThe conditions under which pyrolysis takes place, such as temperature, heating rate, and residence time, can significantly affect the properties of the biochar produced.   More.

Characterization of CoP@P-yeast revealed a crystalline structure with large CoP crystals predominantly localized on the biochar’s surface. This structural trait contributed to its enhanced catalytic stability and performance. Compared to other yeast-derived catalysts, CoP@P-yeast exhibited superior efficiency in both HER and NO₃⁻RR applications. For HER, CoP@P-yeast achieved a low overpotential of −192 mV at a current density of 10 mA/cm², comparable to platinum-based benchmarks but far more cost-effective. Similarly, in NO₃⁻RR, it demonstrated an ammonia production rate of 33 mg-NH₃ h⁻¹ mg-catalyst⁻¹, outperforming many synthetic and biochar-based catalysts.

The stability of CoP@P-yeast under operating conditions also proved notable. During the NO₃⁻RR, the large CoP crystals on the biochar surface resisted degradation better than those embedded within other biochar matrices. This robust performance highlights its potential as a sustainable alternative for industrial electrocatalysis, where stability under harsh conditions is crucial.

In addition to demonstrating the efficacy of P-accumulating yeast as a precursor, this study emphasizes the importance of optimizing yeast culture and processing conditions for electrocatalyst production. The findings suggest that phosphorus-rich bio-organisms can offer scalable solutions for sustainable catalysis, bridging the gap between biological innovation and practical applications.

This research marks a step forward in the integration of biological and material sciences, offering a path toward cost-effective and eco-friendly electrocatalysts. By leveraging the natural properties of yeast and refining synthesis methods, the study provides a blueprint for future advancements in biochar-based technologies for renewable energy and chemical production.

SOURCE: Ojima, et al (2025) Cobalt phosphide-loaded biochar synthesis using phosphate-accumulating yeast and its application as an electrocatalyst. Biotechnology Reports. https://doi.org/10.1016/j.btre.2025.e00874