The incorporation of carbon-fixing materials such as photosynthetic algae in concrete formulations offers a promising strategy toward mitigating the concerningly high carbon footprint of cement. Prior literature suggests that the introduction of up to 0.5 wt % chlorella biological matter (biomatter) in ordinary Portland cement induces a retardation of the composite cement’s strength evolution while enabling a long-term compressive strength comparable to pure cement at a lower carbon footprint. In this work, we provide insights into the fundamental mechanisms governing this retardation effect and reveal a concentration threshold above which the presence of biomatter completely hinders the hydration reactions. We incorporate Chlorella or Spirulina, two algal species with different morphology and composition, in ordinary Portland cement at concentrations ranging between 0.5 and 15 wt % and study the evolution of mechanical properties of the resulting biocomposites over a period of 91 days. The compressive strength in both sets of biocomposites exhibits a concentration-dependent long-term drastic reduction, which plateaus at 5 wt % biomatter content. At and above 5 wt %, all biocomposites show a strength reduction of more than 80% after 91 days of curing compared to pure cement, indicating a permanent hindrance effect on hardening. Characterization of the hydration kinetics and the cured materials shows that both algal biomatters hinder the hydration reactions of calcium silicates, preventing the formation of calcium hydroxide and calcium silicate hydrate, while the secondary reactions of tricalcium aluminate that form ettringite are not affected. We propose that the alkaline conditions during cement hydration lead to the formation of charged glucose-based carbohydrates, which subsequently create a hydrogen bonding network that ultimately encapsulates calcium silicates. This encapsulation prevents the formation of primary hydrate products and thus blocks the hardening of cement. Furthermore, we observe new hydration products with composition and micromorphology deviating from the expected hardened cement compounds. Our analysis provides fundamental insights into the mechanisms that govern the introduction of two carbon-negative algal species as fillers in cement, which are crucial for enabling strategies to overcome the detrimental effects that those fillers have on the mechanical properties of cement.

The increasing consumption of nonrenewable materials urgently calls for the design and fabrication of sustainable alternatives. New generations of materials should be derived from renewable sources, processed using environmentally friendly methods, and designed considering their full life cycle, especially their end-of-life fate. Here, we review recent advances in developing sustainable polymers from biological matter (biomatter), including progress in the extraction and utilization of bioderived monomers and polymers, as well as the emergence of polymers produced directly from unprocessed biomatter (entire cells or tissues). We also discuss applications of sustainable polymers in bioplastics, biocomposites, and cementitious biomaterials, with emphasis on relating their performance to underlying fundamental mechanisms. Finally, we provide a future outlook for sustainable material development, highlighting the need for more accurate and accessible tools for assessing life-cycle impacts and socioeconomic challenges as this field advances. Expected final online publication date for the Annual Review of Materials Research, Volume 53 is July 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Cadmium-free quantum dots (QDs) have been investigated for replacement cadmium-based QDs because of highly toxicity for humans and environmental such as CuInS2/ZnS (CIS/ZnS) core/shell QDs that exhibit tunable emission wavelength and very broad emission spectrum. It often used in solid state lighting and white light-emitting diodes (WLEDs). This work reports on the synthesis of CIS/ZnS core/shell QDs using dodecanethiol (DDT) and zinc stearate as a precursor to form ZnS shell. Moreover, for improving the device stability, we coated SiO2 on CIS/ZnS QDs surface. The crystal structure was analysis by transmission electron microscopy (TEM) and powder X-ray diffractometer (PXRD). The result shows that the emission wavelength of CIS/ZnS is 534 nm and with a high quantum yield (QY) of 107 %. The color rendering index (CRI), correlated color temperature (CCT) and luminous efficacy of SiO2-coated WLED are 73, 4764 K, and 95 lmW−1, respectively. Moreover, high stability of SiO2-coated WLED can be obtained. The result indicates that CIS/ZnS@SiO2 QDs have great potential to development of further WLED application.

CuInS2/ZnS Cd-free quantum dots (QDs) have many characteristics, such as high quantum yield (QY), wide emission peak and adjustable light color. They are suitable for optical conversion materials and applies in solid-state lighting (SSL). However, they are not easily dispersed during encapsulation, resulting in the deviation of light color out of the white light area after encapsulation. In this study, we use thermal injection synthesis method to prepare CuInS2/ZnS and CuInS2/ZnS:Al QDs. In order to improve the dispersion of QDs, solution type of QD/PS-PE-BR-PS copolymer (SEBS) mixture was prepared by mixing QD and SEBS with different ratios (10, 20, and 30 wt%) to form a fluorescent film. The experimental results show that the emission wavelengths and QY of CuInS2/ZnS and CuInS2/ZnS:Al QDs are 533 nm, 84 % and 536 nm, 97 %, respectively. The emission wavelength of CuInS2/ZnS-based fluorescent film is 574 nm, while CuInS2/ZnS:Al-based fluorescent film is 582 nm. The CRI, luminous efficacy, chromaticity coordinates and correlated color temperature of 20 wt% CuInS2/ZnS-based fluorescent film excited by blue chip is 64, 42 lm/W, (0.33, 0.32), and 5443 K, respectively. On the other hand, we find that the CRI of CuInS2/ZnS:Al-based fluorescent film can be improved from 64 to 73, and the luminous efficacy is 51 lm/W.